Which three doses protect older people better: Moderna or Pfizer? McMaster study finds Moderna more effective in long-term-care

Moderna vaccines could better protect older people from COVID-19 infections than those produced by Pfizer, McMaster University researchers have found.

The research team, including professors and study co-corresponding authors Dawn Bowdish and Andrew Costa, tracked 997 long-term-care residents in 17 nursing homes and eight retirement homes in Ontario who had received three mRNA vaccines.

The youngest was 40 years old, while the oldest was over 100.

The team found 17 per cent of study participants were infected with the Omicron variant between December 2021 and May 2022. Of them, most infections (68 per cent) were in residents who had three Pfizer shots, while those with multiple Moderna vaccines or a combination of mRNA shots were less likely to be infected.

More specifically, infection risk decreased by 47 per cent with three doses of Moderna compared to three doses of Pfizer.

When the Omicron wave hit, we found that people who had multiple Moderna vaccines were less likely to get infected," Bowdish told The Spectator.

The study, funded by the Public Health Agency of Canada, also showed having any fourth dose of vaccine reduced the risk of infection.

Bowdish said there are three important findings in the study, which was published as a pre-print in medRxiv and has yet to undergo peer review.

First, Moderna seems to work much better in older adults, and probably the general population ... giving longer-lasting, more protective immunity." This is because there are more of the vaccine ingredients or the mRNA in the Moderna vaccine than in the Pfizer vaccine."

Second, previous infections with a non-Omicron variant don't provide long-lasting protection" against reinfection. This, she noted, is where the role of the second booster comes in, adding that people who had the fourth dose were less likely to be affected" - the team's third key finding.

Mixing and matching vaccines is totally fine, but Pfizer has a certain brand recognition that is not supported by the science," Bowdish, who is also the Canada Research Chair in Aging and Immunity, said in a media release.

As a result of its findings, the Mac team suggests vaccinating the population right at the start of a COVID wave, and monitoring immunity in older adults.

You really want to time your vaccine campaigns with the beginning of a wave to give people maximum protection, which only lasts a few months in the context of Omicron," Bowdish explained.

She also said using our vaccines as wisely as we can" would help better protect the population. That means prioritizing older people for vaccines, and using the right vaccine for the right population.

On top of that, we still have to think about protecting vulnerable people" by masking while socializing indoors, and maintaining precautions.

Even with the vaccines, LTC residents can still get sick, and this is so disruptive to the rest of their care, especially with staffing still being a huge challenge," Bowdish added in the release.

Ritika Dubey is a reporter at The Spectator. rdubey@thespec.com