A healthcare worker administers a dose of the Pfizer-BioNTech Covid-19 vaccine at a vaccination clinic at the PBD Institute Library in PBD, Massachusetts, USA, on Wednesday, January 26, 2022.
Vanessa Leroy | Bloomberg | Getty Images
According to the Food and Drug Administration, an update to the currently approved Covid-19 vaccine may be needed to ensure a higher level of protection as the virus continues to evolve.
The FDA said in a briefing document released before an advisory committee meeting this week that scientists still do not fully understand how covid affects the effectiveness of alternative vaccines. However, mutations in spike proteins, which are used by viruses to attack human cells, have reduced the effectiveness of current vaccines. This is because today’s Covid shots were made in late 2019 to target the spike protein in the main strain of the virus that originated in Wuhan, China.
The FDA’s advisory committee of outside vaccine experts will discuss on Wednesday how the United States could develop a transparent process to recommend changes in vaccine formulations if necessary. Pfizer and Moderna are currently conducting clinical trials of the vaccine based on the omicron variant, the dominant version of the virus worldwide. Omicron and its rapidly spreading subvariant BA.2 have numerous mutations that give them an improved ability to make vaccines and cause infections that usually cause mild illness.
According to the UK Health Security Agency, 25 weeks after the second shot, the effectiveness of two doses of the vaccine Pfizer or Moderna against mild illness from Omicron has dropped from 70% to just 10%. The third dose increases the protection by 75% for about 4 weeks, but then after 15 weeks it decreases from 25% to 40%. According to the Center for Disease Control and Prevention, the effectiveness of two vaccines against hospitalization from Omicron has dropped from 71% to 54% after five months. A third shot increases protection by 91%, which decreases to 78% four months later.
According to the CDC, when vaccines were first approved in December 2020, they were 90% effective in preventing infections and causing symptoms.
The FDA said in the briefing document that it is impossible to predict which variant will become effective and for how long, creating a practical limit to how often vaccines can be changed. Drug regulators also said that clinical trial data should be viewed before approving any changes to vaccine combinations so that they are effective and do not raise safety concerns.
The FDA has proposed using the flu vaccine update process as a guideline on how covid vaccines can be modified in the future. The World Health Organization meets twice a year to analyze flu variants and make recommendations about vaccine formulations. Experts from outside the FDA, the Vaccine and Related Organic Products Advisory Committee, then meet to make their own recommendations for the United States, and the drug regulator then makes a decision based on the committee’s advice. The FDA is not bound by the WHO’s flu vaccine recommendation, but drug regulators usually come to the same conclusion.
However, the FDA said in its briefing document that it may have to consider updating the covid vaccine without prior recommendation from the WHO. It is unclear whether the spread of covidosis will follow a pattern that will lead to global recommendations for vaccine updates, the FDA document said.
The FDA Advisory Committee on Wednesday will also consider whether there could be a fourth coveted shot warranty for minors in the United States. The drug regulator last week approved a fourth Pfizer and Modern Dose for adults aged 50 and over, based on data from Israel, indicating that extra shots reduce adult mortality. The FDA committee has not met to make a recommendation before that decision, and it will not vote on any of the recommendations Wednesday.
Dr. Peter Marks, head of the FDA’s office responsible for vaccine protection and efficacy, said last week that an additional booster dose may be needed in the fall. Public health experts and epidemiologists say the United States could face another wave of covid infection at that time because vaccines weaken immunity and people move indoors to escape the cold weather.