TOPLINE A new study out of South Korea found that taking an AstraZeneca vaccine shot followed by a Pfizer-BioNTech vaccine shot boosted Covid-19 antibody levels six times more than receiving two Astra-Zeneca doses, as some governments around the world are giving the green light to mix Covid-19 vaccine shots for extra protection against the virus.
The study was conducted by the Korea Disease Control and Prevention Agency, and it took a look at the effects of mixing certain vaccine doses and vaccine efficacy against coronavirus variants Alpha, Beta, Gamma and Delta, as first reported by Reuters.
About 499 medical workers took part in the study, with about 200 workers receiving two doses of the AstraZeneca vaccine, 200 workers receiving two doses of the Pfizer-BioNTech vaccine and 100 workers receiving mixed doses of both the vaccines.
All three groups acquired antibodies, with the group that mixed AstraZeneca and Pfizer showing similar levels of antibodies as the group that received the two Pfizer shots.
The study also found that each of the vaccine doses were most effective against the Alpha variant, but showed decreased effectiveness between 2 ½ to 6 times on Beta, Gamma and Delta variants.
Back in June, Oxford University led a study to find out if mixing and matching vaccines was viable. It found that taking an AstraZeneca vaccine shot followed by a Pfizer shot created the highest T-cell response, which are immune cells that attack and destroy infected cells. The vaccine combo also generated more antibodies than taking a Pfizer shot followed by an AstraZeneca shot. Both the Oxford University study and Korea Disease Control and Prevention Agency study show that vaccines can still provide a strong immunity response to the virus if mixed and matched. The United States Centers for Disease Control does not recommend mixing doses from different vaccines since it has not yet evaluated if that practice is safe and effective. However, some countries like Germany and Spain allow for mixed shots, allowing people to receive Pfizer and Moderna shots even after they have already gotten AstraZeneca’s first dose. Canada’s health officials also started to recommend mixing vaccine shots last month, if people are unable to take two of the same vaccine doses.
As the Delta variant continues to grow internationally, more people are reporting taking multiple vaccine doses. Chancellor of Germany Angela Merkel received the Moderna jab at the end of June, a few months after she received her first AstraZeneca shot. One U.S. doctor received the one-shot Johnson & Johnson vaccine in Seattle, but then, after moving to Canada, got one shot of the Pfizer vaccine for added protection, according to a report by CNBC. The U.S. does not consider people who have had different doses of vaccines as fully vaccinated.
WHAT TO WATCH OUT FOR
Pfizer said it will be creating a booster shot to target the Delta variant. Trials for the booster shot began in Nashville on Monday. Moderna also announced it will be developing a booster shot, with trial results expected by September. Some doctors are even encouraging those who received the Johnson & Johnson vaccine to consider getting either a Pfizer or Moderna booster shot, even though it is unclear how the booster shots may work with other vaccines.
By Kimberlee Speakman, Forbes Staff