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Washington, US Vice President-elect <keyword id="180909" type="PERSON" weightage="20" keywordseo="Kamala-Harris">Kamala Harris</keyword> has received the first dose of the <keyword id="9253744" type="UNKNOWN" weightage="20" keywordseo="Moderna-vaccine">Moderna vaccine</keyword> against the novel coronavirus. According to the Biden-Harris transition team, Harris was vaccinated on Tuesday by Patricia Cummings, a clinical nurse manager at the United Medical Center. In a tweet late Tuesday, Harris said: "Today I got the <keyword id="8904563" type="UNKNOWN" weightage="20" keywordseo="covid-19-vaccine">Covid-19 vaccine</keyword>. I am incredibly grateful to our frontline health care workers, scientists, and researchers who made this moment possible. "When you're able to take the vaccine, get it. This is about saving lives." Harris' vaccination, which was also broadcast live on TV, came almost a week after President-elect Joe Biden received his. After receiving the shot, Harris said she wants to "encourage everyone to get the vaccine. It is relatively painless. It happens really quickly. It is safe". The Vice President-elect also confirmed that her husband, Doug Emhoff, would be receiving the first dose of the <keyword id="4912868" type="LOCATION" weightage="20" keywordseo="moderna">Moderna</keyword> vaccine on Tuesday, CNN reported. "I want to remind people that right in your community is where you can take the vaccine, where you will receive the vaccine, by folks you may know, folks who are otherwise working in the same hospital where your children were born. "Folks who are working in the same hospital where an elderly relative received the kind of care that they needed," CNN quoted Harris as saying. The <keyword id="6356255" type="COMPANY" weightage="20" keywordseo="us-food-and-drug-administration">US Food and Drug Administration</keyword> has granted emergency use authorization (EUA) for two Covid-19 vaccines: one from Pfizer/BioNTech and one from Moderna. The two vaccines have shown similar efficacy levels of near 95%, and both require two doses administered several weeks apart. On December 18, Vice President Mike Pence, Second Lady Karen Pence, Surgeon General Jerome Adams,House of Representatives Speaker Nancy Pelosi and Senate Majority Leader Mitch McConnell received the Pfizer-BioNTech vaccination all on live TV, in a bid to instill confidence among Americans. President Donald Trump, who had tested positive for the virus in October, is yet to get vaccinated. As of Wednesday morning, the US, currently the hardest-hit country in the world by the pandemic, has registered a total of 19,299,960 confirmed coronavirus cases and 334,830 deaths, according to the Johns Hopkins University. Both tallies are the highest in the world. SEE ALSO: <a href="https://www.businessinsider.in/stock-market/news/top-stocks-to-watch-sbi-hdfc-bank-wipro-ril-future-retail-tcs-jindal-stainless-upl-irctc-and-others/articleshow/80019871.cms">Top stocks to watch — SBI, HDFC Bank, Wipro, RIL, Future Retail, TCS, Jindal Stainless, UPL, IRCTC, and others</a> <a href="https://www.businessinsider.in/india/news/india-detects-14-new-cases-of-uk-covid-19-strain-putting-the-tally-at-20/articleshow/80020163.cms">India detects 14 new cases of UK COVID-19 strain, putting the tally at 20India detects 14 new cases of UK COVID-19 strain, putting the tally at 20</a> <a href="https://www.businessinsider.in/business/startups/news/2021-could-finally-be-the-year-of-indias-tech-ipos-as-startups-like-zomato-delhivery-policybazaar-head-for-the-public-markets/slidelist/80019978.cms">2021 could finally be the year of India’s tech IPOs as startups like Zomato, Delhivery, Policybazaar head for the public markets</a>

Kamala Harris receives the first dose of COVID-19 vaccine

<ul class="summary-list"><li>Millions of people worldwide have had one shot of two-dose COVID-19 vaccines. </li><li><keyword id="44612" type="CITY" weightage="60" keywordseo="Pfizer">Pfizer</keyword> and <keyword id="4912868" type="PERSON" weightage="60" keywordseo="moderna">Moderna</keyword>'s vaccines are likely 80% effective against symptomatic COVID-19 after one dose.</li><li>A single <keyword id="6409874" type="COMPANY" weightage="60" keywordseo="astrazeneca">AstraZeneca</keyword> shot is probably at least 70% effective at preventing symptomatic COVID-19.</li></ul>More than <a href="https://covid.cdc.gov/covid-data-tracker/#vaccinations" target="_blank" rel="noopener">183 million Americans</a> and more than <a href="https://coronavirus.data.gov.uk/details/vaccinations" target="_blank" rel="noopener">45 million Britons</a> have received their first dose of a two-shot COVID-19 <keyword id="24209" type="PERSON" weightage="60" keywordseo="vaccine">vaccine</keyword>.The US has authorized vaccines from <a href="https://www.businessinsider.com/moderna-coronavirus-vaccine-wins-us-fda-emergency-use-authorization-2020-12" target="_blank" rel="noopener">Moderna</a> and <a href="https://www.businessinsider.com/fda-authorize-pfizer-covid-vaccine-biontech-alex-azar-2020-12" target="_blank" rel="noopener">Pfizer-BioNTech</a>, while the UK has <a href="https://www.businessinsider.com/pfizer-and-biontech-covid-19-vaccines-approved-by-uk-regulator-2020-11" target="_blank" rel="noopener">authorized Pfizer's</a> shot as well as one made by <a href="https://www.businessinsider.com/oxford-astrazeneca-coronavirus-authorized-emergency-use-in-uk-2020-12" target="_blank" rel="noopener">AstraZeneca and Oxford University</a>. Both countries have <a href="https://www.businessinsider.com/expert-panel-recommends-fda-ok-jjs-coronavirus-covid-vaccine-2021-2" target="_blank" rel="noopener">authorized Johnson &amp; Johnson's</a> vaccine, which is a single dose.The UK is <a href="https://www.businessinsider.com/should-we-delay-second-vaccine-dose-first-dose-fauci-mutation-2021-2" target="_blank" rel="noopener">delaying the second dose</a> of the vaccines for up to 12 weeks for most people to prioritize giving people their first shot because of an initial shortage of vaccines. In the US, the <a href="https://www.cdc.gov/vaccines/covid-19/info-by-product/clinical-considerations.html" target="_blank" rel="noopener">Centers for Disease Control and Prevention (CDC) has recommended</a> giving second doses of Pfizer's vaccine 21 days after the first, and 28 days after the first for Moderna, with an interval of up to six weeks if "necessary.The <keyword id="6355729" type="ORGANIZATION" weightage="60" keywordseo="data">data</keyword> for how well the vaccines work after one dose isn't clear cut - it depends on what you're measuring, and when you're measuring it. Stephen Evans, a professor of medical statistics at the London School of Hygiene &amp; Tropical Medicine and a former drug-safety committee member at the European Medicines Agency, helped Insider break down the data.Evans said the Food and Drug Administration (FDA) presentation of the data from late-stage trials of each vaccine was generally the best data available. This is how much protection one shot of each vaccine gives you, based on that data.<div type="image" title="Vaccine" height="2082" width="2777" msid="82219588" hostid="261"></div><h2>Pfizer-BioNTech: at least 80%</h2>Pfizer's shot was 52.4% effective at protecting against COVID-19 with symptoms between the first and second dose, <a href="https://www.fda.gov/media/144337/download" target="_blank" rel="noopener">according to the FDA documents</a>. But the 52.4% figure includes the 11 days before protection kicks in after the first dose, so the real percentage could well be higher.The true value lies between 29.5% and 84.5%, according to the FDA documents. There was a wide range because not many people caught COVID-19 in the trial during this time period.<div type="image" title="Professor Stephen Evans" height="1193" width="1193" msid="81471155" hostid="261"></div>Pfizer's shot was 100% effective at protecting against hospitalization and death. This was based on a small number though - only four people got severe COVID-19 in the trial after receiving placebo rather than the vaccine.Evans said there was "pretty clear evidence" that you get at least 80% protection - and "probably" better than 90% - for Pfizer's vaccine against COVID-19 with symptoms after a single dose. He said you couldn't be absolutely sure what happens after 21 days because it hadn't been fully tested.Evans said this was based on his overall reading of the trial data used by the FDA in their briefing document before authorization.<h2>Moderna: at least 80%</h2>Moderna's vaccine was 69.5% effective at preventing COVID-19 with symptoms between the first and second dose, with a true value between 43.5% and 84.5%. There was a fairly wide range because the number of people that caught COVID-19 in the trial during this time period was low.The 69.5% figure includes the 13 days before protection starts, so the real percentage could be higher.There were a small number of people in Moderna's trial - about 7% - that didn't get their second dose for unknown reasons. In this group, the shot was 50.8% effective at preventing COVID-19 with symptoms for up to 14 days after the first dose and 92.1% effective after 14 days.It is unclear how well one shot of the vaccine protects against hospitalization and death because not many people got severe COVID-19 - two in the vaccine group and four in placebo. Evans said that you get at least 80% protection - and probably better than 90% - for Moderna's vaccine against COVID-19 with symptoms after a single dose for 28 days. After 28 days it was unclear because it hadn't been tested. Again, this was based on his overall reading of the FDA data, he said.<h2>AstraZeneca: more than 70%</h2>Evans said it was harder to ascertain a figure for AstraZeneca's vaccine because late-stage trials used differing study designs, and a large US study was ongoing. The FDA also has not yet presented the data for the shot in the same way it has done for other vaccines.A single dose of AstraZeneca's shot was 76% effective at protecting against COVID-19 with symptoms for at least 90 days, according to late-stage-trial data <a href="https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(21)00432-3/fulltext" target="_blank" rel="noopener">published in The Lancet</a> on February 19. The study authors also reported that one dose provided 100% protection against hospitalization, but the numbers were small. Based on his reading of existing studies, Evans said the single-dose efficacy for AstraZeneca's vaccine was probably <a href="https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(21)00528-6/fulltext-" target="_blank" rel="noopener">at least 70%</a> against COVID-19 with symptoms for the first 90 days. After this time period, it's unclear, he said.<h2>Johnson &amp; Johnson: 66%</h2><a href="https://www.businessinsider.com/johnson-and-johnson-covid-19-vaccine-arguably-the-best-2021-2" target="_blank" rel="noopener">J&amp;J</a> looked at protection against moderate to severe COVID-19 <a href="https://www.businessinsider.com/fda-expert-panel-recommends-johnson-johnson-coronavirus-vaccine-for-ok-2021-2" target="_blank" rel="noopener">in trials</a>, rather than symptomatic COVID-19, like Pfizer, Moderna, and AstraZeneca.Protection kicked in at 14 days and was <a href="https://www.fda.gov/advisory-committees/advisory-committee-calendar/vaccines-and-related-biological-products-advisory-committee-february-26-2021-meeting-announcement" target="_blank" rel="noopener">66.1% effective at 28 days</a>. The vaccine's efficacy varied depending on the country it was used in - it was <a href="https://www.businessinsider.com/jj-single-dose-covid-19-vaccine-full-study-results-2021-2" target="_blank" rel="noopener">72% effective in the US</a> but 64% and 68% effective in South Africa and Brazil, respectively. These countries both have <keyword id="1754604" type="PERSON" weightage="60" keywordseo="coronavirus">coronavirus</keyword> variants circulating that could partially evade antibodies.<h2>What percentage efficacy means</h2>Percentage efficacy for vaccines refers to the proportion of people that get full protection after a vaccine. With 80% efficacy, 80% of people have full protection, and 20% don't.For those who get full protection the first time around, the second shot improves the quality of the immune response and its durability.For the people who don't get full protection with the first shot, some will get full protection after the second dose. Some people won't ever get full protection from a vaccine because their immune system doesn't respond at all.<h2>The latest real-world data: One shot significantly reduces infections and transmission</h2><ul><li><a href="https://www.businessinsider.com/one-dose-astrazeneca-or-pfizer-vaccine-protects-against-covid-19-2021-4" target="_blank" rel="noopener noreferrer">A UK study</a> found Pfizer or AstraZeneca's vaccine cut COVID-19 infections with symptoms by 72% after one dose, and protection probably held up for 10 weeks. Protection from Pfizer's vaccine rose to 90% after two doses. The study hasn't been peer-reviewed. </li><li>A <a href="https://www.cdc.gov/mmwr/volumes/70/wr/mm7013e3.htm?s_cid=mm7013e3_w" target="_blank" rel="noopener noreferrer">US study</a> of essential workers found that a single dose of Pfizer of Moderna's COVID-19 vaccines were 80% effective against all coronavirus infections from 14 days.</li><li>A <a href="https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(21)00677-2/fulltext?utm_campaign=lancetcovid21&amp;utm_content=163707807&amp;utm_medium=social&amp;utm_source=twitter&amp;hss_channel=tw-27013292nnel=tw-27013292" target="_blank" rel="noopener noreferrer">Scottish study</a> found that a single dose of Pfizer's vaccine was 91% effective against hospitalization at 28 to 34 days following vaccination. One dose of AstraZeneca's vaccine was 88% effective against hospital admissions after the same time period.</li><li><a href="https://www.businessinsider.com/one-shot-astrazeneca-pfizer-vaccine-halves-covid-spread-study-2021-4" target="_blank" rel="noopener noreferrer">A UK study</a> found that a single dose of either Pfizer or AstraZeneca's vaccine cut spread of symptomatic COVID-19 within a household by up to 50%.</li><li>A <a href="https://www.businessinsider.com/one-shot-pfizer-astrazeneca-coronavirus-vaccine-effective-south-korea-2021-5" target="_blank" rel="noopener noreferrer">South Korean study</a> found one dose of Pfizer's vaccine was 89.7% effective at preventing COVID-19 in South Koreans aged over 60, at least two weeks after vaccination. AstraZeneca's vaccine was 86% effective at preventing COVID-19 after one dose. The severity of illness that the shots protected against was unclear - generally they're more effective at preventing COVID-19 infections that caused hospitalization or death.</li><li>An <a href="https://www.bmj.com/content/373/bmj.n1088" target="_blank" rel="noopener noreferrer">English study </a>found that a single dose of either Pfizer or AstraZeneca's vaccine was about 80% effective at preventing hospitalization in people over 70-years-old. Protection lasted for at least 6 weeks, including against the Alpha variant first identified in the UK. </li><li>An <a href="https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2780700?widget=personalizedcontent&amp;previousarticle=0le=0" target="_blank" rel="noopener noreferrer">Israel study </a>showed that Pfizer's vaccine was 54% effective against symptomatic COVID-19, from 13 days to 24 days after vaccination, a figure comparable to the late stage trial data presented to the FDA.</li><li>A <a href="https://www.thelancet.com/journals/laninf/article/PIIS1473-3099(21)00289-9/fulltext" target="_blank" rel="noopener">UK study</a> estimated that a single dose of either Pfizer or AstraZeneca's vaccine was between 56% and 62% effective at preventing COVID-19 infection caused by <a href="https://www.businessinsider.com/coronavirus-variants-uk-south-africa-brazil-us-facts-questions-2021-1" target="_blank" rel="noopener">the Alpha variant</a> in people over 75 years-old, four to seven weeks after the first dose. The severity of illness that the shots protected against was unclear, but probably included asymptomatic infections.</li><li>A <a href="https://www.thelancet.com/journals/laninf/article/PIIS1473-3099(21)00330-3/fulltext" target="_blank" rel="noopener">UK study </a>estimated that one dose of Pfizer vaccine was 79.3% effective at reducing the risk of hospitalization from COVID-19 in people aged over 80. A single shot of AstraZeneca's was 80.4% effective, the researchers said.</li><li>An <a href="https://khub.net/documents/135939561/430986542/RCGP+VE+riskgroups+paper.pdf/a6b54cd9-419d-9b63-e2bf-5dc796f5a91f" target="_blank" rel="noopener">English study</a> found that a single dose of Pfizer or AstraZeneca's COVID-19 vaccines was about 60% effective at preventing symptomatic COVID-19 in people with underlying illness that weaken the immune response. These underlying conditions included diabetes, severe asthma, chronic heart disease, chronic kidney disease, chronic liver disease, neurological disease, blood cancer, and HIV.</li></ul><h2>Newest data suggests second shot provides better protection against variants</h2>Real-word data from the <a href="https://www.businessinsider.com/india-variant-pfizer-astrazeneca-covid-vaccine-one-shot-effectiveness-2021-5" target="_blank" rel="noopener">UK posted</a> May 23 by Public <keyword id="6354750" type="UNKNOWN" weightage="60" keywordseo="health">Health</keyword> England showed that Pfizer's and AstraZeneca's COVID-19 vaccines worked better against the variants when two doses were given rather than just one. Both vaccines were 30% effective against COVID-19 with symptoms caused by the Delta variant, first identified in India, three weeks after the first dose. This was boosted to between 60% and 88% effectiveness two weeks after the second dose. The two vaccines were 50% effective against COVID-19 with symptoms against the variant first found in the UK, Alpha, three weeks after the first dose. This increased to between 66% and 93% two weeks after the second dose.Dr. Anthony Fauci, President Joe Biden's chief medical advisor, <a href="https://www.businessinsider.com/delta-variant-covid-coronavirus-india-fauci-second-shot-dose-2021-6" target="_blank" rel="noopener">said on June 8</a> that getting two doses of COVID-19 vaccines would stop the Delta variant from spreading across the US. In the UK, Professor Deborah Dunn-Walters, chair of the British Society for Immunology COVID-19 Taskforce, <a href="https://www.sciencemediacentre.org/expert-reaction-to-research-letter-looking-at-blood-neutralising-antibody-levels-from-people-vaccinated-with-one-or-two-doses-of-the-pfizer-vaccine-against-different-variants-of-sars-cov-2-including/" target="_blank" rel="noopener">said in a statement</a> on June 4 that two doses of Pfizer's vaccine were <a href="https://www.businessinsider.com/pfizer-covid-19-vaccine-antibody-response-variant-lab-study-2021-6" target="_blank" rel="noopener">"critical for protection"</a> against emerging strains of the virus.

How much protection you get from one shot of the Pfizer, AstraZeneca, and Moderna vaccines, according to the best available data

With the vaccination drive for adolescents entering its third day, as per the Co-WIN portal 1,06,27,277 children in the 15 to 18 years' age group have been vaccinated with the first Covid-19 vaccine dose so far. According to the government's Co-WIN portal, 1,33,64,030 children have registered so far for the first dose of vaccine. Union Health Minister Mansukh Mandaviya has lauded the spirit of the youngsters for receiving the vaccine and said "superb enthusiasm among 'Young India' for vaccination". "More than 1 crore youngsters between 15-18 years' age group have received first dose of Covid-19 vaccines that, too, on their third day of vaccination drive. I appeal to all eligible young friends to get vaccinated at the earliest," Mandaviya added in a tweet. As of now, only Bharat Biotech's indigenously-made Covaxin is available for vaccinating the 15-18 years' age group. According to the Health Ministry, additional doses of Covaxin will be sent to the states and UTs for administering the vaccine to this population category. Prime Minister Narendra Modi had announced on December 25 that vaccination for the 15-18 years' age group will begin from January 3. The vaccination process for a third precautionary dose of vaccine for health workers, frontline workers and vulnerable senior citizens will begin from January 10. SEE ALSO <a href="https://www.businessinsider.in/business/startups/news/amazon-backed-good-glamm-group-will-invest-200-crore-in-influencer-marketing/articleshow/88690749.cms" data-type="tilCustomLink">Amazon-backed Good Glamm Group acquires 2 more startups, intends to invest ₹200 crore to boost influencer marketing</a> <a href="https://www.businessinsider.in/business/telecom/news/elon-musks-starlink-faces-its-first-setback-in-india-even-before-launch/articleshow/88702976.cms" data-type="tilCustomLink">Elon Musk’s Starlink faces its first setback in India even before launch</a> <a href="https://www.businessinsider.in/tech/enterprise/news/infosys-is-expected-to-set-the-bar-slightly-higher-for-tcs-hcl-tech-and-others/articleshow/88703083.cms" data-type="tilCustomLink">Infosys is expected to set the bar slightly higher for TCS, HCL Tech and others</a>

One crore teens between 15-18 years have received their first dose of COVID-19 vaccine

<ul class="summary-list"><li>A single shot of <keyword id="44612" type="CITY" weightage="60" keywordseo="Pfizer">Pfizer</keyword> or <keyword id="4912868" type="PERSON" weightage="60" keywordseo="moderna">Moderna</keyword>'s vaccine yields high protection for people who've had COVID-19.</li><li>That's probably because their bodies are responding to a viral threat they've seen before.</li><li>One expert said giving people who've had COVID-19 a second dose was "kind of a wasted shot."</li></ul>In the race to get <keyword id="1754604" type="PERSON" weightage="60" keywordseo="coronavirus">coronavirus</keyword> vaccines into arms as quickly as possible, scientists think they've found a way to accelerate the process: Give the people who've already had COVID-19 just one dose.Most vaccine-eligible Americans are getting either <a href="https://www.businessinsider.com/pfizer-moderna-covid-19-vaccines-comparison-how-the-shots-compare-2020-12">Pfizer's or Moderna</a>'s vaccine, both of which require two doses administered several weeks apart. But a growing chorus of researchers now agrees that a single dose of either vaccine will generate a sufficient immune response among people who've already had the coronavirus. Giving them the second dose, research suggests, might essentially waste a good shot."For those who've been infected and recovered, which is tens of millions of people, they'll only need one shot, which will make the vaccine go even further," Dr. James Hildreth, the president of Meharry Medical College, told Insider.Hildreth served on the <a href="https://www.businessinsider.com/live-updates-fda-advisory-committee-moderna-coronavirus-vaccine-2020-12">Food and Drug Administration advisory committee</a> that recommended all three authorized coronavirus vaccines in the US. The third, from <a href="https://www.businessinsider.com/coronavirus-vaccines-compared-pfizer-moderna-johnson-and-johnson-2021-1">Johnson &amp; Johnson</a>, is a one-shot vaccine, so people who've had COVID-19 would get a single dose of that no matter what.Given that more than 30 million Americans are known to have had COVID-19, that could be up to 15 million Pfizer or Moderna shots that could go to other people.<h2>New research backs up the one-shot strategy</h2>Once a person has had COVID-19, their immune system should recognize the virus if it invades a second time. So when a vaccine spurs the body to start producing <keyword id="102007" type="TECHNOLOGY" weightage="60" keywordseo="Antibodies">antibodies</keyword> again, it's logical that the immune system would mount a stronger and quicker defense.Indeed, a <a href="https://www.nature.com/articles/s41591-021-01325-6">new peer-reviewed study</a> found similar antibody responses among individuals who'd had COVID-19 and received a single dose of Pfizer's vaccine and individuals who received two doses of the vaccine but had never gotten COVID-19.The researchers concluded that "a second vaccine dose did not offer previously infected individuals a substantially greater benefit over a single dose."After the first dose, nearly 37% of the study participants who'd had COVID-19 experienced significant side effects versus 25% of study participants who'd never had COVID-19. After the second dose, there wasn't as much difference between the two groups: 51% versus 59%, respectively.The researchers found that "fever and chills were more common among previously infected vaccine recipients after the first dose, whereas infection-naive individuals were more likely to experience headache, dizziness, or lightheadedness after the second dose."<h2>'The first dose ends up serving as the booster'</h2><div type="image" title="Vaccine" height="2828" width="4800" msid="81865999" hostid="261"></div>In a letter in the <a href="https://www.nejm.org/doi/full/10.1056/NEJMc2101667?query=featured_home">New England Journal of Medicine</a> last month, 32 researchers from the Icahn School of Medicine at Mount Sinai wrote that a single-dose strategy for people who'd already had the virus "requires investigation."The team found in <a href="https://www.medrxiv.org/content/10.1101/2021.01.29.21250653v1.full.pdf">a small study</a> that people who'd previously had COVID-19 developed 10 to 45 times as many antibodies after their first dose of Pfizer or Moderna's vaccine as the average uninfected person did. The research is still awaiting peer review."The first dose ends up serving as the booster," Dr. Jeremy Faust, an emergency-medicine physician at Brigham and Women's hospital, told Insider. "If you've been infected, it's very likely that one dose would be pretty damn good for quite a while."There are a few caveats, though: People may need to confirm that they still have antibodies if they were sick a while ago, since antibody levels wane over time. An antibody test would also be required for those who suspect they had COVID-19 but never tested positive. If that antibody test comes back positive, the second shot is most likely redundant."What is the point?" Akiko Iwasaki, an immunobiologist at Yale University, told Insider. "It's kind of a wasted shot."<h2>'This is where the policy lags <keyword id="41551" type="ENTERTAINMENT" weightage="100" keywordseo="science">science</keyword>'</h2><div type="image" title="UK testing antibody" height="2667" width="4000" msid="81441454" hostid="261"></div>France in February began <a href="https://www.has-sante.fr/jcms/p_3237456/en/une-seule-dose-de-vaccin-pour-les-personnes-ayant-deja-ete-infectees-par-le-sars-cov-2">recommending a single vaccine dose</a> for people who've had COVID-19.By then, the Mount Sinai research was out, and <a href="https://www.medrxiv.org/content/10.1101/2021.01.30.21250843v1">another preliminary study</a> had also discovered high antibody levels among healthcare workers who'd had COVID-19 before receiving their first shot.Dr. Mohammad Sajadi, a coauthor of that study, <a href="https://www.businessinsider.com/people-who-had-coronavirus-only-need-one-vaccine-dose-2021-2">told Insider</a> that COVID-19 patients typically develop antibodies about two to three weeks after their initial infection. But the healthcare workers showed high antibody levels a week after their first shot."What that shows you is that individuals who had a prior COVID infection have what we call a recall response or a memory response," Sajadi said. "For most infections, the second time you see that microorganism, you should get a faster response."Then in late February, <a href="https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(21)00501-8/fulltext">a UK study</a> found roughly equal antibody levels among people who'd received the first dose of Pfizer's vaccine and had never gotten COVID-19 and those who'd had COVID-19 but weren't vaccinated yet. After the people who'd had COVID-19 got their first shot, their antibody levels were 140 times their peak levels before the vaccine.Yet most countries, including the US, don't yet recommend a single-dose regimen for people who've had COVID-19."This is where the policy lags science," Iwasaki said.Dr. Anthony Fauci, the director of the National Institute of Allergy and Infectious Diseases, <a href="https://www.nbcnews.com/meet-the-press/meet-press-february-21-2021-n1258472">told NBC News in February</a> that the idea was worth considering."The data looked really quite impressive - that if you've been infected and then you get a single dose, the boost that you get with that single dose is really enormous," Fauci said. "That is one thing that you might want to consider, but we really want to look carefully at the data first."<h2>Concerns about long-term <keyword id="48619" type="PERSON" weightage="60" keywordseo="Immunity">immunity</keyword></h2><div type="image" title="covid vaccine card cdc" height="2702" width="3911" msid="81441456" hostid="261"></div>Since scientists haven't had much time to follow up with vaccine recipients, there's no consensus yet about how long vaccine-induced immunity lasts. This uncertainty is one reason experts are hesitant to advocate anything other than the standard two-dose regimens of the Pfizer and Moderna vaccines.Delaying or skipping the second dose places a lot of pressure on the first dose to provide solid, long-term immune protection, Princeton University researchers <a href="https://science.sciencemag.org/content/early/2021/03/08/science.abg8663">wrote</a> Tuesday. They expressed concern that switching up the dosing regimen could lead to a "broad range" of outcomes among vaccinated people.But Iwasaki said people who'd had COVID-19 could probably wait months before getting their second shot - if they need one at all."There just isn't any need to do it so early," she said.Scientists are also optimistic that even though antibody levels are known to wane over time, T cells will confer long-term protection for those who've had COVID-19. Like antibodies, T cells have impressive powers of recollection that can help the immune system recognize and reattack the coronavirus.A recent study found that people who previously had COVID-19 mounted a stronger T-cell response to one shot of Pfizer's vaccine than people who'd never gotten infected did.

You Searched For "first doses of covid 19 vaccine" and got 4 results

Kamala Harris receives the first dose of COVID-19 vaccine

IANS

How much protection you get from one shot of the Pfizer, AstraZeneca, and Moderna vaccines, according to the best available data

Dr. Catherine Schuster-Bruce

One crore teens between 15-18 years have received their first dose of COVID-19 vaccine

IANS

The research is in: People who've already had COVID-19 need just one shot

Aria Bendix,Hilary Brueck

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