New findings suggest that testing for COVID-19 following vaccination will still be necessary, as contracting a COVID-19 infection is still possible following full vaccination.
The new research from Rockefeller University reports results from ongoing monitoring which revealed that two fully vaccinated individuals tested positive for COVID-19. The researchers say that these “breakthrough” cases may be driven by the rapid evolution of the virus, and that ongoing testing of people who have been vaccinated will still be needed to help prevent future outbreaks.
The findings have been published in the New England Journal of Medicine.
Infection after immunisation
Both immunised individuals who contracted COVID-19 had received two doses of either the Moderna or the Pfizer vaccine, with the second dose occurring more than two weeks before the positive test.
One of the individuals was initially asymptomatic, going on to developed typical COVID-19 symptoms, and the other developed symptoms prior to testing. Both individuals recovered at home, which the researchers say is an outcome consistent with evidence suggesting vaccination is effective in preventing severe cases of the disease.
Genome sequencing revealed multiple mutations in both viral samples, including the E484K variant in one individual, first identified in South Africa and Brazil, and the S477N variant in the other individual.
Robert B. Darnell, The Robert and Harriet Heilbrunn Professor, who led the research with immunologist Michel C. Nussenzweig, virologist Paul Bieniasz, and geneticist Richard P. Lifton, said: “These patients got vaccinated, had great immune responses, and nonetheless broke through with a clinical infection.”
The observations suggest it is likely a small but ongoing risk among vaccinated individuals, and there is the possibility that they may continue to spread the virus.
Darnell said: “The idea that we could be entirely done with testing in the post-vaccine world is probably not a good one right now; for example, even fully vaccinated people who develop respiratory symptoms should consider getting tested for COVID-19.
“Conversely, exposure to individuals with known infection, even if fully vaccinated, should be taken seriously and again individuals should consider getting tested. Given the scope of the pandemic, there is a huge amount of virus in the world right now, meaning a huge opportunity for mutations to develop and spread. That is going to be a challenge for the developers of vaccines over the next months and years.”
