Over 179 million Americans have had their first shot of COVID-19 vaccine. More than 44 million Britons have also received the COVID-19 vaccination.The US has approved vaccines from Moderna, Pfizer-BioNTech, and the UK has approved Pfizer's shot along with one made by AstraZeneca. Johnson & Johnson's vaccine has been approved by both countries. It is a single-dose vaccine.Due to a shortage of vaccines, the UK will delay the second dose for 12 weeks. The Centers for Disease Control and Prevention in the USA recommends giving the second dose of Pfizer's vaccine 21 to 28 days after the initial one. Moderna can be given after this interval for up to six weeks if it is "unavoidable".It is not clear how effective vaccines are after one dose. This depends on what measurement you make and when. Insider was assisted by Stephen Evans, a professor of medicine statistics at London School of Hygiene & Tropical Medicine, and a former member of the European Medicines Agency's drug-safety advisory committee.Evans stated that the Food and Drug Administration presented data from the late-stage trials for each vaccine as the most reliable data. Based on this data, you can calculate how much protection each shot of vaccine provides.Pfizer-BioNTech: Minimum 80 percentAccording to FDA documents, Pfizer's shot was 52.4% effective in protecting against COVID-19 symptoms that developed between the first dose and the second dose. The FDA documents show that the actual percentage may be higher as the 52.4% figure does not include the 11 days of protection that kicks in following the first dose.According to FDA documents, the true value lies somewhere between 29.5 percent - 84.5 percent. This was because COVID-19 was not commonly caught during the trial.Pfizer's shot was 100% effective in protecting against death and hospitalization. The trial involved a small number of people, but only four received severe COVID-19 after they were given the vaccine.Evans stated that there is "pretty strong evidence" that the vaccine against COVID-19 from Pfizer provides at least 80 percent protection. The vaccine also offers "probably" better than 90% protection for those who have symptoms. Because it had not been thoroughly tested, you can't know what happens after 21-days.Evans stated that this was based upon his general reading of trial data used in FDA's briefing document prior to authorization.Moderna: At least 80 percentModerna's vaccine prevented COVID-19 symptoms from the first to second dose. It was 69.5 percent effective. The true value ranged between 43.5 percent to 84.5 percent. This was due to the low number of COVID-19-infected people in the trial.The 13-day period before protection begins is included in the 69.5 percent, so it's possible that the actual percentage could be higher.Moderna's trial had a small number of participants, approximately 7 percent who didn't receive their second dose due to unknown reasons. The shot was effective in preventing COVID-19 symptoms up to 14 days after the initial dose, and 92.1 percent after that time.Because not many people received severe COVID-19 in either the vaccine or placebo groups, it isn't clear how effective one shot of vaccine protection against death and hospitalization.Evans stated that Moderna's vaccine against COVID-19 provides at least 80 percent protection, and possibly better than 90% for those who have symptoms. The Moderna vaccine is available in 28-day doses. It wasn't tested after 28 days, so it was not clear. He said that this was based upon his overall analysis of FDA data.AstraZeneca: More than 70%Evans stated that it was difficult to determine a figure for AstraZeneca’s vaccine due to the fact that late-stage trials had different study designs and an ongoing large US study. The FDA has not yet provided data on the shot in the same manner it did for other vaccines.Late-stage trial data published in The Lancet, February 19, showed that AstraZeneca's shot was 76 per cent effective in protecting against COVID-19 symptoms for at most 90 days. Although the study authors reported that one dose of AstraZeneca provided 100% protection against hospitalizations, these numbers were not large.Evans based his analysis of the existing studies stated that AstraZeneca vaccine's single-dose efficacy was at least 70% against COVID-19 symptoms for the first 90 day. It's not clear what happens after this period, he stated.Johnson & Johnson: 66 per centJ&J focused on COVID-19 protection in trials rather than symptoms like Moderna, Pfizer, or AstraZeneca.Protection began at 14 days, and it was 66.1 percent effective after 28 days. The effectiveness of the vaccine varied depending on where it was administered. It was effective at 72 percent in the US, but only 64 percent and 68% in South Africa and Brazil respectively. Both countries have coronavirus variants that could partially evade antibodies.What does it mean to be a percentage of efficacy?The percentage of people who receive full protection from vaccines is called the percent efficacy. 80 percent people are protected with vaccines that have an 80 percent efficacy. The remaining 20 percent do not.The second shot is for those who have received full protection the first round. It improves the quality and durability of the immune response.Some people will receive full protection even if they don't get the first shot. Because their immune system isn't responding, some people may not get the full protection they need.Latest real-world dаta: One shot dramatically reduces transmission and infectionsA UK study showed that AstraZeneca or Pfizer's vaccine reduced COVID-19 symptoms by 72 per cent after one dose. Protection probably lasted for 10 weeks. After two doses, Pfizer's vaccine protected 90 percent. The study was not peer-reviewed.An American study found that one dose of Pfizer Moderna's COVID-19 vaccines was 80 percent effective in preventing all coronavirus infection within 14 days.According to a Scottish study, a single dose Pfizer's vaccine is 91 percent effective in preventing hospitalization within 28-34 days after vaccination. A single dose of AstraZeneca’s vaccine was 88 per cent effective against hospital admissions within the same time frame.A UK study showed that one dose of AstraZeneca or Pfizer's vaccine could reduce the spread of symptoms of COVID-19 in a household by as much as 50%.One dose of Pfizer's vaccine proved to be 89.7 per cent effective in preventing COVID-19 among South Koreans over 60. This was according to a South Korean study. It also showed that the vaccine had a two-week effectiveness rate for preventing COVID-19. After one dose, AstraZeneca's vaccine prevented COVID-19 at an 86 percent rate. Although it was not clear what the shots prevented from, they are more effective in preventing COVID-19 infection that causes hospitalizations or death.A study in England found that one dose of AstraZeneca or Pfizer's vaccine prevented hospitalizations for people over 70 years old. Protection was effective for at least six weeks, even against the Alpha variant that was first discovered in the UK.A study in Israel showed that Pfizer's vaccine against COVID-19 symptoms was effective at 54 percent. This figure is comparable to data from late-stage trials presented to FDA.A UK study found that one dose of AstraZeneca or Pfizer's vaccine prevented COVID-19 infected people over 75. This was four to seven weeks after receiving the first dose. Although the severity of the illness that shots protected against was not known, it is likely to include asymptomatic infections.One dose of Pfizer vaccine is 79.3 per cent effective in reducing hospitalizations from COVID-19, according to a UK study. The researchers found that a single dose of AstraZeneca's vaccine was 80.4 percent efficient.The latest data suggest that a second shot offers better protection against variantsPublic Health England posted real-word data May 23 from the UK showing that two doses of AstraZeneca and Pfizer's COVID-19 vaccines against these variants performed better than one. The vaccines were 30% effective against COVID-19 symptoms due to the Delta variant. This variant was first identified in India three weeks after the first dose.Two weeks later, the effectiveness was increased to 60 percent to 88 percent. Three weeks after the first dose, the two vaccines proved to be 50 percent effective against COVID-19. They also provided symptoms against Alpha, the variant that was first discovered in the UK. Two weeks later, the rate rose to between 66 and 93 per cent.Chief medical advisor to President Joe Biden, Dr. Anthony Fauci, stated that two doses COVID-19 vaccines were necessary to stop the spread of the Delta variant.Professor Deborah Dunn-Walters (chair of the British Society for Immunology COVID-19 Taskforce) stated in a statement that two doses Pfizer's vaccine are "critical for protection" from emerging strains.Business Insider originally published this article.More Business Insider:
