Vaccines work. They ward off severe illness and death. But they do not make health care workers invulnerable to breakthrough infections, according to a research letter in JAMA Open Network.
Although COVID-19 vaccines work, they do not guarantee that a vaccinated person will not be reinfected, according to a research letter published in JAMA Network Open\that examined breakthrough infections among health care workers (HCWs).1 Investigators reviewed data from 5312 fully vaccinated and 690 unvaccinated HCWs at the Hadassah University Medical Center in Jerusalem, Israel. The vaccinated workers received 2 doses of the Pfizer/BioNTech vaccine.
The results reinforce the main message health care officials in most countries want the public to hear: vaccines work. Investigators found that 27 of the fully vaccinated staff became reinfected with COVID-19 (0.5%), compared with 69 of the unvaccinated staff did (10%). Contact tracing for the breakthrough infections found that 15 of the 27 vaccinated staff who experienced breakthrough infections became infected by a member of their household.
“This case-control study found that exposure to SARS-CoV-2–positive household members was a risk factor associated with infection among vaccinated HCWs,” the research letter states. “Household exposure is usually longer and closer than casual exposure or exposure at work and does not include masking or distancing, thus exposing one to a higher infectious dose and being more contagious.”
Investigators argue that their findings suggest that individuals exposed to someone in their household who has tested positive for COVID-19 be quarantined. “The findings of this case-control study suggest reconsideration of quarantining vaccinated [individuals] who have had significant exposure to household members who are positive for SARS-CoV-2 infection,” the research letter states. “This policy has already been implemented successfully in our hospital. Coupled with the current emergence of the SARS-CoV-2 Delta variant in Israel and worldwide, our proposal should apply not only to HCWs but to the general population.”