A healthcare worker administers a dose of the Pfizer covid-19 vaccine to a man at the Sanford Civic Center. With the emergence of the Omicron covid-19 variant in several countries, including the United States, the US Centers for Disease Control (CDC) encouraged all vaccinated adults to receive their Covid-19 booster shots.
Paul Hennessy | LightRocket | Getty Images
Pfizer and BioNTech released more human data on Friday indicating that the omicron BA.5 boosters perform better than the old Covid shots.
People older than 55 who received the new booster had about four times more antibodies directed at omicron BA.5 than people in the same age group who received the old vaccine, according to the companies. Antibodies are an important part of the body’s defense system, blocking the virus from invading cells.
The study compared 36 people over the age of 55 who received the omicron booster as their fourth dose with 40 people from the same age group who received the original vaccine as their fourth shot.
In addition, people aged 18 to 55 who received the booster had 9.5 times more antibodies directed against omicron BA.5 than they did before receiving the shot. These participants were not compared to people of the same age who received the old vaccines.
Pfizer and BioNTech also found that people with and without previous Covid infections had a significant increase in their antibody levels after the omicron boosters. But those who had no previous infection had a greater increase in their antibodies, according to the companies.
Pfizer and BioNTech released the first human data in October showing that the omicron boosters trigger a better immune response. But two small, independent studies from Columbia and Harvard cast doubt on whether the shots were really a significant improvement. They found the new boosters and the old shots did about the same against the omicron BA.5.
The Food and Drug Administration said the Columbia and Harvard studies were too small to draw any definitive conclusions about the boosters. The scientific community and public health officials are closely following data on the boosters because the FDA approved them without direct human data.
The FDA instead relied on human data from a similar shot that targeted the original version of omicron, the BA.1, as well as animal studies that directly examined the BA.5 shot.
Pfizer and Moderna originally developed the BA.1 shot, but the FDA asked them to switch gears over the summer and develop a booster targeting BA.5 because it had become the dominant variant. As a consequence, there was not enough time for the companies to launch clinical trials and provide data before FDA approval.
The FDA moved quickly to roll out new shots targeting omicron by the fall in an effort to stave off another wave of infections, hospitalizations and deaths this fall and winter.
The White House, the FDA and the Centers for Disease Control and Prevention have repeatedly said the boosters should provide better protection this fall and winter because they are directly matched to the prevailing strain of the virus for the first time since December 2020.
The boosters are called bivalent shots because they target both the omicron BA.5 variant as well as the original virus strain that emerged in China in 2019. The old vaccines are called monovalent shots because they only target the original Covid strain.
The monovalent vaccines no longer provide meaningful protection against infection and mild disease because the virus has evolved so much. They are still generally effective against serious illness and hospitalization, although this protection has also declined over time.