A recent study that tested four COVID-19 vaccines found that BioNTech SE (NASDAQ: BNTX) and Pfizer Inc. (NYSE:PFE) shots elicited the strongest immune response. The researchers from the National Center for Zoonotic Diseases, the Onom Foundation, and Stanford University also concluded that Sinopharm Group’s (OTCMKTS: SHTDY) vaccine left recipients more prone to a breakthrough infection.

How researchers conducted the study

The study was conducted in Mongolia among 192 immunized people. Because of the alpha variant, Mongolia experienced a surge in infections during the summer. About 89.2% of vaccinated adults in Mongolia had received Sinopharm.

The four vaccines triggered the production of antibodies against the virus at different levels. For instance, vaccines by Sinopharm and Sputnik V activated low levels of antibody production. AstraZeneca Plc triggered intermediate antibody production.

Scientists are looking into the reason for different immune responses among the vaccines. They speculate that it could be because of the levels of the active ingredient in the shots or the period between the initial and second shots.

Sputnik argues that the researchers did the tests poorly

The differences in how vaccines were given could have also impacted the results making the results flawed. According to the Russian Direct Investment Fund, which supported the creation of Sputnik’s vaccines and played a role in its supply, the time between Sputnik V administration and measuring antibodies was longer than for the other vaccines; hence the comparison should not be trusted. Tests subjects who received the Sputnik shots were also about ten years older.

The study authors recommended administering booster doses with stronger vaccines to control the spread of the virus in Mongolia and the rest of the world. Researchers also say that using vaccines with a lower efficacy could still help reduce mortality, hospitalization, and the number of infections.

Sam Fazelli, a Bloomberg intelligence analyst, points out that the researchers didn’t give intervals between the doses or regimens they used. They also didn’t study the cellular immune response.

Although Mongolia has vaccinated more people than any other Asian country, it also has the highest number of COVID-19 cases. Authorities claim that this is due to the high numbers of unvaccinated younger people and the country’s complacency after infections first went down. The Sinopharm vaccine is another factor as it failed to live up to expectations.