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The Covid-19 vaccine from Pfizer Inc. and BioNTech SE remains highly effective six months after its second dose, an indication that protection could last for an even longer period. The findings, released on Thursday, emerged from a continuing review of how volunteers in the shot’s late-stage trial were faring and whether they contracted Covid-19 with symptoms. In the rush to introduce vaccines for a new virus, companies and other vaccine researchers were unable to determine how long shots would provide protection, or whether booster shots would be needed to ensure protection. (Hopkins, 4/1)

Real-world and trial data continue to indicate that the vaccine is highly effective, especially against COVID-19 hospitalization and death. The companies said updated trial results showed the vaccine offered 100% protection against severe disease as defined by the CDC, and 95.3% as defined by the FDA. 927 symptomatic COVID-19 cases were detected among the trial's 46,307 participants — 850 of which came from the placebo group and 77 of which came from the vaccine group. (4/1)

n the US, the first two available Covid-19 vaccines were those from Pfizer/BioNTech and Moderna. Both vaccines have very high “efficacy rates” of around 95 percent. But the third vaccine introduced in the US, from Johnson & Johnson, has a much lower efficacy rate: just 66 percent. Look at those numbers next to each other, and it’s natural to conclude that one of them is considerably worse. Why settle for 66 percent when you can have 95 percent? But that isn’t the right way to understand a vaccine’s efficacy rate, or to even understand what a vaccine does. And public health experts say that if you really want to know which vaccine is the best one, efficacy isn’t actually the most important number at all. (Marshall and Mas, 4/1)

The United States may not need AstraZeneca’s COVID-19 vaccine, even if it wins U.S. regulatory approval, Anthony Fauci, the nation’s top infectious disease doctor told Reuters on Thursday. The vaccine, once hailed as another milestone in the fight against the COVID-19 pandemic, has been dogged by questions since late last year, even as it has been authorized for use by dozens of countries, not including United States. Fauci, director of the National Institute of Allergy and Infectious Diseases and chief medical adviser to the White House, said the United States has enough contracts with other vaccine makers to vaccinate its entire population, and possibly enough for booster shots in the fall. (Steenhuysen, 4/2)

British regulators on Thursday said they have identified 30 cases of rare blood clot events after the use of the AstraZeneca COVID-19 vaccine, 25 more than the agency previously reported. The Medicines and Healthcare products Regulatory Agency said it had received no such reports of clotting events following use of the vaccine made by BioNTech SE and Pfizer Inc. (4/2)

At the headquarters of biotechnology company Novavax, scientists are developing what they hope could soon be another Covid-19 vaccine for the United States and the world. Data from the company's large-scale Phase 3 clinical trial of the vaccine in the US and Mexico are expected this month, but the timeline depends on how quickly it accumulates data on the prevalence of disease in trial areas. The company's vaccine against Covid-19 has been a year in the making, Dr. Gregory Glenn, president of research and development for Novavax, told CNN. The work began even before the world realized it faced a pandemic. (Howard, 4/1)