Sinopharm's COVID-19 Shot Offers Weaker Protection Among Elderly: Study

By Reuters Staff

July 26, 2021

(Reuters) - Sinopharm's COVID-19 vaccine was less effective in offering protection against the disease among the elderly, according to the results of a Hungarian study.

The study of 450 participants who had received two doses of the vaccine showed measurable antibody levels were present in about 90% of people under the age of 50, but the protection reduced as age increased.

The researchers found the likelihood of producing virus-neutralizing antibodies dropped with age, and they were undetectable in about 25% of people aged 60, and 50% of those aged 80, according to the preprint published on the medRxiv website earlier this week.

With so many elderly subjects unable to produce any protective antibodies, the results suggest that measures should be put in place to prevent an outbreak of COVID-19 among them, the study's authors said.

But the authors warned that the reliable estimation of a direct relationship between the risk of COVID-19 disease, hospitalization, or death and the antibody levels after vaccination is extremely difficult.

Sinopharm, formally known as China National Pharmaceutical Group, was not immediately available for comment.

The two-dose vaccine, which is based on inactivated virus plus an adjuvant, is one of the most widely used COVID-19 shots in China, and Sinopharm has agreed to provide up to 170 million doses of the shot to the global vaccine sharing scheme COVAX through to the middle of 2022.

Another recent study published on medRxiv ( that the vaccine elicited weaker antibody responses against the Delta variant, which was first detected in India and is now the dominant variant worldwide.

SOURCE: medRxiv, online July 19, 2021.