Italian HCW study reaffirms Pfizer-BioNTech effectiveness against COVID-19

By Jocelyn Solis-MoreiraMay 26 2021

Real-world data from Pasquale Stefanizzi of Aldo Moro University in Italy and colleagues confirm that the Pfizer-BioNTech vaccine effectively prevents COVID-19 infection.

Their results showed healthcare workers were 61.9% protected against SARS-CoV-2 infection 14 to 20 days after the first dose. Vaccine effectiveness jumped to 96% after the second dose.

“These results may influence vaccination willingness among HCWs, as a vaccine that confers disease prevention can be regarded as a form of personal protective equipment. Moreover, a vaccine that prevents infection could dramatically limit the circulation of the virus in the hospital setting. Vaccination can therefore be perceived both as a means of self-protection and as an ethical obligation to guarantee the safety of others, especially high-risk hospital patients,” concluded the researchers.

The study “BNT162b2 mRNA Covid-19 vaccine effectiveness in the prevention of SARS-CoV-2 infection: a preliminary report” was recently published in The Journal of Infectious Diseases.

Study: BNT162b2 mRNA Covid-19 vaccine effectiveness in the prevention of SARS-CoV-2 infection: a preliminary report. Image Credit: Cortex-film / Shutterstock

How they did it

The study took place in Italy’s Bari Policlinico General University Hospital, with vaccinations available to healthcare workers starting on December 27, 2020.

At the time, COVID-19 vaccinations were not mandatory. Healthcare workers requested a vaccination through an online form with first and second-dose appointments made through the Hygiene Department.

Two doses of the Pfizer-BioNTech mRNA vaccine were administered intramuscularly in the deltoid muscle, with injections spread out in a 21-day time period. The researchers followed up with healthcare workers who received all their shots between December 27, 2020, and January 31, 2021. Healthcare workers who had a history of COVID-19 infection were excluded from the study.

The research team followed up with healthcare workers one month after vaccination to record any vaccine side-effects or infections.

In total, there were 2,034 healthcare workers enrolled in the study. About 79% were vaccinated, and 21% were unvaccinated.

Regardless of vaccination status, all healthcare workers were required to continue using personal protective equipment. Healthcare workers also were screened for COVID-19 infection every 14 days — regardless of symptom presentation.

Vaccination provides better protection against SARS-CoV-2 infection

Researchers recorded 121 COVID-19 infections after about 60 days of follow-up. In the unvaccinated group, 14 were asymptomatic, and 50 showed COVID-19 symptoms. The vaccinated group had about 17 healthcare workers who were asymptomatic and 37 symptomatic.

The likelihood of developing infection was higher in the unvaccinated group than in the vaccinated group.

Results showed the vaccine was 61.9% effective in preventing infection 14 to 20 days after the first dose. Effectiveness increased from 61.9% to 96% a week after the second dose.

There were no severe or long-term vaccine side effects reported in this study.

Given the usefulness of COVID-19 vaccines in protecting against severe disease, the researchers conclude that a change in policy mandating vaccination in healthcare workers is needed. For Italy, mandatory COVID-19 vaccination for healthcare workers involved in pandemic emergencies was executed on March 31, 2021.