The coronavirus variant first discovered in the United Kingdom is rapidly spreading in the United States, Pfizer announces it intends to produce two billion doses of its Covid-19 vaccine, and more.

• South Africa on Sunday announced it has temporarily suspended its rollout of the Covid-19 vaccine developed by AstraZeneca pending further investigation, after a controversial preprint analysis suggested the vaccine "provides minimal protection" against mild cases of Covid-19 caused by the B.1.351 coronavirus variant dominant in the country. In the analysis—which included 1,765 participants in South Africa with an average age of 31—researchers found that 19 of the 39 participants who tested positive for B.1.351 had received the AstraZeneca vaccine, while 20 had received a placebo, implying an efficacy rate of about 10%, according to Shabir Madhi, principal investigator on the trial and dean of the medical school at the University of the Witwatersrand. However, the Wall Street Journal notes that the trial is considered too small—and its participants too young—to make broad conclusions about the vaccine's efficacy, particularly regarding rates of severe illness, hospitalization, or death. Moreover, according to STAT News, certain data included in the analysis appears unreliable, with some estimates on the vaccine's efficacy presented with confidence intervals of between 50% and 60%. And Madhi himself added that it may be "reckless" to allow doses of AstraZeneca's vaccine to expire without using them. That said, Sarah Gilbert—a professor of vaccinology at the University of Oxford who is working with AstraZeneca on the vaccine—said the company is working on a new version of the vaccine to combat the B.1.351 variant and expects "to show that the new version of the vaccine will generate antibodies and recognize the new variant" this year. Meanwhile, in another preprint paper released Friday, Oxford researchers found the AstraZeneca vaccine had 74.6% efficacy against the B.1.1.7 coronavirus variant that was first identified in the United Kingdom, which is similar to but slightly lower than its efficacy against earlier variants of the virus (Herper, STAT News, 2/7; Steinhauser, Wall Street Journal, 2/7; Mueller et. al., New York Times, 2/7; Ellyatt, CNBC, 2/8; Choi, The Hill, 2/7; Mueller/Robbins, New York Times, 2/5).

• The B.1.1.7 variant of the novel coronavirus is rapidly spreading throughout the United States, according to a preprint study released Sunday. For the study, researchers from CDC and Helix analyzed about 500,000 coronavirus tests and hundreds of genomes and found the variant is 35% to 46% more transmissible than earlier and currently more common variants in the United States. The researchers projected that B.1.1.7 could become the dominant variant of the new coronavirus in the United States within a month, adding that new cases of B.1.1.7 are doubling in the United States every 10 days. Nicholas Davies—an epidemiologist at the London School of Hygiene and Tropical Medicine who was not involved in the study—warned, "There could indeed be a very serious situation developing in a matter of months or weeks." Noting that data in the United States "is patchier than in Britain and other countries," he added, "if [this] data [is] representative, there may be limited time to act" (Zimmer, New York Times, 2/7; Rummler, Axios, 2/7).

• FDA on Tuesday said it is limiting the scope of its authorization for convalescent plasma as a treatment for Covid-19. According to FDA's revised emergency use authorization for the treatment, providers may now use only high-titer convalescent plasma can be used for treatment, and they may use it only for patients who are hospitalized with Covid-19 early on in the course of the disease or who have impaired humoral immunity and can't produce a sufficient endogenous antibody response. According to FDA, the agency based its revision on recent data from clinical trials, including a trial from the Mayo Clinic that found higher-titer plasma was associated with a lower mortality risk than lower-titer plasma, and that patients who received plasma and were not on ventilation had a lower fatality risk than those who were on ventilation (Walker, Medscape, 2/5).

• Pfizer on Tuesday announced it intends to make two billion doses of its Covid-19 vaccine—developed in partnership with BioNTech—in 2021 and expects to generate about $15 billion in revenue from its vaccine sales. Albert Bourla, CEO of Pfizer, added that the two billion-dose projection was a conservative estimate, and that the company is working on ways to exceed its target. Pfizer also said it expects to cut the amount of time it takes to produce its vaccine in half, from about 110 days to about 60 (Mishra/Erman, Reuters, 2/2; Duffy, CNN, 2/2; Weise, USA Today, 2/7).

• Moderna last week said it's proposing filling its Covid-19 vaccine "vials with additional doses of vaccine, up to 15 doses versus the current 10 doses." The proposal aims to address issues with capacity, according to Stephen Hoge, president of Moderna. Hoge noted that, when it comes to capacity issues, "beyond the amount of drug product available, is how many vials you can fill in a given period of time." However, Moderna said it will "need to have further discussions with the FDA to assure the agency's comfort with this approach before implementing" (Singh, Reuters, 2/1).