(Reuters) – Protective antibody levels decline faster in recipients of the mRNA COVID-19 vaccine from Pfizer/BioNTech than in COVID-19 survivors, according to doctors at one of Israel’s largest HMOs.
The research team tracked antibody levels in 2,653 adults who received two doses of the vaccine and in 4,361 COVID-19 survivors who were never vaccinated. Antibody levels fell by up to 40% per month in vaccinated participants, versus less than 5% per month in so-called convalescents.
After six months, about 84% of vaccine recipients still had detectable antibodies, whereas roughly 90% of convalescents still had detectable antibodies after nine months.
Dr. Ariel Israel of Leumit Health Services, coauthor of a reported posted on medRxiv ahead of peer review, noted that antibodies are not the immune system’s only weapon against the virus. Still, he said, the data suggests that antibody protection in Pfizer vaccine recipients wanes at a higher rate than in COVID-19 survivors.
Leumit researchers had previously reported that breakthrough infection rates increase starting about five months after vaccination. Dr. Israel said the combined data argues for a booster shot five months after the second injection, especially for high-risk individuals.
SOURCE: https://bit.ly/2XP2Dwi medRxiv, online August 22, 2021.