Two doses of the Pfizer COVID-19 vaccine induce a "very good" antibody response against the SARS-CoV-2 variants, according to a study on 180 health care workers in Finland.

The research, published in the journal Nature Communications on June 28, found that the immune response was as strong against the Alpha variant first identified in the UK, as against the original virus found in Wuhan, China in 2019. The immune response was somewhat decreased against the Beta variant first found in South Africa, but the vaccine generated neutralising antibodies that give relatively good protection against the variant. A neutralising antibody is responsible for defending cells from pathogens.

The researchers, including those from the University of Turku and University of Helsinki, studied the immune response induced by the coronavirus vaccinations, which started in Finland in December last year. They analysed vaccine responses in 180 health care workers, each of whom received two doses of the Pfizer-Biontech mRNA vaccine, and compared it with immune response in recovered COVID-19 patients. The vaccine participants were aged 20-65 years, 149 were females and 31 were males. The group of recovered COVID-19 patients comprised 50 volunteers, aged 19-93, with 33 among them females and 17 males.

All vaccinated subjects were found to have an excellent antibody level against the original virus after two vaccine doses. The immune response was just as strong against the Alpha variant of the virus. "The study demonstrates the efficiency of the COVID-19 vaccine and its ability to induce antibody responses in the working-age population regardless of their age or sex. The vaccine is one of the most effective I have ever studied," said Ilkka Julkunen, professor at the University of Turku.

Although the immune response against the Beta variant was weaker, the vaccinated subjects did have neutralising antibodies that give relatively good protection against the variant. "After two doses, the immune response created by the COVID-19 vaccine was even better than after a coronavirus infection with mild symptoms," said Pinja Jalkanen, a doctoral candidate at the University of Turku. Professor Anu Kantele from Helsinki University Hospital noted that it is very promising that nearly all of the vaccinated subjects had even a small amount of neutralising antibodies against the Beta variant.

The study will continue to follow-up on immune response and protection against other variants circulating around the world, such as the delta variant first found in India. The research will focus on the analysis of the antibodies of other available coronavirus vaccines.