Israeli Study Finds First Dose of Pfizer/BioNTech Vaccine Highly Effective

A study conducted in Israel, which has already vaccinated a large percentage of its population, has found that a single dose of Pfizer/BioNTech’s COVID-19 vaccine is highly effective at reducing infection, lending more support to the strategy of delaying second doses to increase initial vaccinations.

According to the Sheba Medical Center, which submitted findings from its study to The Lancet, a single shot of the Pfizer vaccine demonstrated a 75 percent reduction of COVID-19 infection overall among 7,214 vaccinated healthcare workers 15 to 28 days after the dose was given. That effectiveness was even higher (85 percent) for reducing symptomatic cases of infection, the researchers found.

In their study, the authors compared infection rates in healthcare workers who had been vaccinated with those who did not receive the vaccine. Importantly, they also tracked the time between vaccination and onset of infection.

“Our data show substantial early reductions in SARS-CoV-2 infection and symptomatic COVID-19 rates following first vaccine dose administration. Early reductions of COVID-19 rates provide support [for] delaying the second dose in countries facing vaccine shortages and scarce resources, so as to allow higher population coverage with a single dose,” the researchers said.

They noted that a longer follow-up is needed to determine the duration of protection a single dose provides and cautioned that because the study did not involve active laboratory surveillance, some asymptomatic cases are likely to have been missed.

The findings, though not yet peer-reviewed, bolster the argument that second doses of Pfizer’s vaccine should be delayed to conserve the supply and ramp up initial inoculations, a tactic already employed by the UK. The FDA does not currently support the strategy, saying that the data seen to date show the two-dose vaccine regimen should be used.

“Although further research is needed, overall these new findings should provide reassurance around the UK’s decision to offer the two doses of the vaccine 12 weeks apart,” said Deborah Dunn-Walters, chair of the British Society for Immunology COVID-19 and Immunology Taskforce.

“While the results of this study show that a good level of immunity is present after one dose … it is still the case that the highest and longest lasting protection from getting ill with COVID-19 will only be provided by getting two doses of the vaccine. It is critical that all people eligible for COVID vaccination do return to get their second dose,” she said.

Read the letter to The Lancet here: bit.ly/3s8Rjoz. — James Miessler