People 60 years of age and older who were originally vaccinated with two doses of Pfizer-BioNTech COVID-19 were better protected against the Omicoron coronavirus variant after administration of Moderna than another dose of Pfizer-BioNTech.
These results are accordingly to intermediate data from a small but randomized controlled clinical trial in Singapore and published this week in the journal Clinical Infectious Diseases.
A study involving 98 healthy adults cannot determine whether the Moderna booster is superior to the Pfizer-BioNTech booster for the elderly, or whether the mixing and combining strategy is inherently better. It also focuses exclusively on antibody levels, which may or may not lead to significant differences in infection rates and other clinical differences. It also followed people for only 28 days after the booster, so it’s unclear whether the side of the Moderna amp will withstand over time.
However, the study’s authors, led by Barnaby Young of Singapore’s National Center for Infectious Diseases, report that the beneficial effect seen in the transition from Pfizer-BioNTech to Moderna was significant enough that they didn’t expect it to disappear with more participants. This also follows from other studies that have suggested that joint gain – this is also heterologous gain – can generate slightly other antibodies and reduce the incidence of SARS-CoV-2 infection in people 60 years and older.
For a new study, Young and colleagues looked at antibody levels in adults of all ages who received two doses of Pfizer-BioNTech vaccine against COVID-19 between six and nine months before receiving a booster dose. The researchers excluded people from the test if they had a compromised immune system or had signs of previous SARS-CoV-2 infections (presence of antibodies against N).
Of the 98 participants, 50 received another dose of Pfizer-BioNTech for their booster (homologous booster), and the remaining 48 received a Moderna booster (heterologous booster). The authors looked at the resulting antibody response on the day of revaccination, seven days and 28 days later. In particular, they compared total levels of antibodies that target a key portion of the SARS-CoV-2 spike protein, called the receptor-binding domain. They also looked at levels of neutralizing antibodies against a number of specific variants of SARS-CoV-2, from ancestral strains to alpha, beta, delta and omicron.
A little bigger boost
Overall, the heterologous group had slightly higher overall antibody levels than the homologous group, about 40 percent higher on day 7 and 30 percent higher on day 28, although confidence intervals overlapped. But when the authors divided the groups by age, they found that the advantage was solely from differences in the group of 60 years and older. Antibody levels were equivalent among young participants, regardless of booster type.
Among those aged 60 and older were 24 participants with homologically amplified and 23 heterologous participants. Seven days after the booster, heterologous participants had twice as many antibodies as the homologous group, and were 60 percent higher at day 28.
Elderly participants with heterologous enhancement also had higher levels of neutralizing antibodies against all tested variants of SARS-CoV-2 – with the largest difference compared to omicron, which is known to inhibit immune responses derived from the vaccine. Seven days later, the level of inhibition of neutralizing antibodies was 89 percent in the group with heterologous enhancement compared with 64 percent in the group with homologous enhancement. After 28 days, the prevalence ranged from 84 percent in the group with heterologous gain to 73 percent in the group with homologous gain.
Overall, Young and co-authors concluded: “In particular, for vulnerable older age groups, the heterologous COVID-19 booster vaccine regimen causes higher antibody titers against adhesions and a stronger neutralizing antibody response against the highly infectious Omicron variant (2020 percent above neutrons). ) than a homologous booster circuit ”.
The trial is still ongoing, so the authors will continue to add participants and data. They intend to re-evaluate the antibody response in all participants six months and 12 months after the booster. They will add to the study of people who originally received the Moderna vaccine to see if the transition to the Pfizer-BioNTech vaccine offers a booster.