Preprint study shows significant vaccine efficacy waning in adolescents
Yesterday a new preprint study out of Israel showed the efficacy of the Pfizer-BioNTech vaccine waned in 12- to 17-year-olds in a similar pattern seen in adult recipients. Within 5 month after completing the initial two-dose vaccinations series, protection against infection with SARS-CoV-2 dropped to 58%. The study was published on the preprint server medRxiv.
The study took place between Jun 15 and Dec 8, 2021, when the Delta variant became the dominant strain in Israel. Cases were patients ages 12 to 16 who had a positive PCR test. The study participants included 129,909 patients served by Maccabi Healthcare Services (MHS), the second-largest healthcare organization in Israel.
Overall, vaccinated adolescents had a notably lower percent of tests that were positive for COVID-19, the authors said, with 6.6% of tests among unvaccinated individuals coming back positive, compared with less than 1.4% for those who received their second dose 14 to149 days before the test, and 3.6% for those who received their second dose more than 150 days before the test.
The peak protection provided by the vaccine was between 2 weeks and 3 months after the second dose, and the effectiveness of the vaccine against infection was subsequently reduced to 75% (95% confidence interval [CI]: 71% to 79%) and 58% (95% CI: 52% to 64%) 90 to149 days and 150 to180 days following receipt of the second dose, respectively.
"Long-term protection conferred by the vaccine was reduced to 75-78% against infection and symptomatic infection, respectively, 3 to 5 months after the second dose, and waned to 58% against infection and 65% against COVID-19 after 5 months," the authors said.
Jan 5 medRxiv study
UK detects human H5 avian flu case
The United Kingdom's Health Security Agency (HSA) today reported a human H5 avian flu infection, which involves a person who had very close and regular contact with sick birds. The infection was detected during routine monitoring of people who have been around sick birds.
In a statement, the HSA said the patient is well and is self-isolating. Contact tracing has found no evidence of further spread.
Laboratory tests revealed the virus is the H5 type found in birds. The UK's Animal and Plant Health Agency (APHA) had identified an H5N1 outbreak in the individual's flock of birds, which have all been culled. The United Kingdom is among the several countries in Europe to report several recent H5N1 detections in poultry and wild birds.
So far, tests on the human isolate haven't confirmed H5N1. The HSA added that though the H5 case is the first involving the strain in Britain, similar cases have been reported from other parts of the world.
Isabel Oliver, MD, the HSA's chief scientific officer, said in the statement, "Currently there is no evidence that this strain detected in the UK can spread from person to person, but we know that viruses evolve all the time and we continue to monitor the situation closely. We have followed up all of this individual’s contacts and have not identified any onward spread."