The COVID-19 vaccine developed by British drugmaker AstraZeneca Plc and Oxford University will likely be authorized for emergency use in the United States in April, the chief adviser for the U.S. COVID-19 vaccine program said on Wednesday.
Operation Warp Speed chief adviser Dr. Moncef Slaoui said recruitment for the British drugmaker's late-stage U.S. trial is almost complete with over 29,000 participants enrolled.
"We project, if everything goes well with readout and emergency use authorization may be granted somewhere in April," Slaoui said.
British regulators approved AstraZeneca's vaccine Wednesday, the first country in the world to do so, based in part on unpublished data.
Several scientists have raised doubts about the robustness of results from its British and Brazilian trials, showing the shot was 90% effective in a sub-group of trial participants. That group, by error initially, received a half dose followed by a full dose. But the efficacy was 62% if the full dose was given twice, as it was for most participants.
Frequently Asked Questions
A vaccine works by mimicking a natural infection. A vaccine not only induces immune response to protect people from any future COVID-19 infection, but also helps quickly build herd immunity to put an end to the pandemic. Herd immunity occurs when a sufficient percentage of a population becomes immune to a disease, making the spread of disease from person to person unlikely. The good news is that SARS-CoV-2 virus has been fairly stable, which increases the viability of a vaccine.
There are broadly four types of vaccine — one, a vaccine based on the whole virus (this could be either inactivated, or an attenuated [weakened] virus vaccine); two, a non-replicating viral vector vaccine that uses a benign virus as vector that carries the antigen of SARS-CoV; three, nucleic-acid vaccines that have genetic material like DNA and RNA of antigens like spike protein given to a person, helping human cells decode genetic material and produce the vaccine; and four, protein subunit vaccine wherein the recombinant proteins of SARS-COV-2 along with an adjuvant (booster) is given as a vaccine.
Vaccine development is a long, complex process. Unlike drugs that are given to people with a diseased, vaccines are given to healthy people and also vulnerable sections such as children, pregnant women and the elderly. So rigorous tests are compulsory. History says that the fastest time it took to develop a vaccine is five years, but it usually takes double or sometimes triple that time.
Slaoui said it would ultimately be up to the U.S. Food and Drug Administration as to how to evaluate the vaccine for U.S. authorization.
Slaoui was also cautious about whether the United States should implement similar guidance as the U.K. regulators to space out the second dose of Pfizer Inc's by as much as 12 weeks, longer than what was studied in clinical trials.
While early data suggests that people have some protection against the virus after receiving their first dose, the length of time that protection lasts has not been studied, Slaoui said.
Officials said that 14 million doses of Pfizer's and Moderna's have been distributed to states, short of their goal to send enough doses to vaccinate 20 million Americans this month.Only about 2 million Americans have been vaccinated thus far and officials said they were still studying why immunizations were slower than they anticipated.