How effective are the new COVID vaccine booster shots against the Pirola variant?

 

As the COVID-19 pandemic continues to evolve, new variants of the virus emerge and pose new challenges for public health. One of the latest variants, called BA.2.86 or "Pirola", has been detected in several countries, including Canada, and has been classified as a variant under monitoring by the World Health Organization (WHO).

Pirola is a highly mutated variant that belongs to the Omicron family of sub-lineages. It has more than 30 mutations in the spike protein, which is the part of the virus that attaches to human cells and allows infection. Some of these mutations may affect the ability of the virus to evade the immune response generated by previous infection or vaccination.

So, how well do the new COVID vaccine booster shots protect against Pirola? The answer is not clear yet, as there is limited data on the effectiveness of the updated vaccines against this variant. However, some experts are optimistic that the boosters will offer some protection, especially against severe disease and hospitalization.

The new booster shots are designed to target the XBB variants — strains of the virus descended from the original Omicron variant — which are now the most common form in circulation. Three vaccine manufacturers, Moderna, Pfizer and Novavax, will offer the revised shots for this fall, which virtually all children and adults are eligible for.

According to Health Canada, these updated vaccines are expected to provide better protection against XBB variants than the original vaccines, which were based on the ancestral strain of the virus. However, they may not be as effective against Pirola as they are against XBB variants, since Pirola has more mutations that could reduce vaccine efficacy.

Dr. Allison McGeer, an infectious disease specialist at Mount Sinai Hospital in Toronto, says that even if the boosters are not perfect against Pirola, they will still be beneficial. "The more people who get vaccinated, the less transmission there is, and the less chance there is for new variants to emerge," she says.

McGeer adds that getting a booster shot will also help protect against other respiratory viruses that may circulate in the fall and winter, such as influenza and respiratory syncytial virus (RSV). "It's not just about COVID-19," she says. "It's about keeping yourself and your community healthy."

The National Advisory Committee on Immunization (NACI) recommends that Canadians get another COVID-19 booster shot this fall, with updated vaccines expected in the months ahead. The next round of vaccines will likely be monovalent — meaning they will specifically target the Omicron family of sub-lineages that are still circulating globally.

NACI's new guidance states that Canadians should wait to get a booster at least six months after a previous vaccine dose or a known SARS-CoV-2 infection — whichever came later. However, some provinces have shortened this interval to three months for certain groups of people who are at higher risk of infection or severe disease.

To book your COVID vaccine booster shot appointment, visit your provincial or territorial website or contact your local public health unit. You can also check with your primary health-care provider or pharmacy if they offer vaccination services.