Wondering if a fourth shot may help ward off variants COVID-19, and what your expectations should be? We share some research published in recent studies.
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Some Canadian provinces are opening eligibility to fourth doses of COVID-19 vaccines. However, research points to limitations of the impact they may have on the highly contagious Omicron BA.5, the subvariant driving the summer's first surge around the country.
With many members of the public requesting access to additional doses, some provincial governments are expanding eligibility from only immunocompromised and older Canadians to anyone over the age of 18.
This move contradicts the National Advisory Committee on Immunization (NACI)'s recommendations that only those at highest risk of severe COVID-19 be given a second booster and that younger Canadians wait until the fall to get vaccinated.
While data indicate that a third dose offers a significant increase in protection from infection, hospitalization and death, for most (even vulnerable groups) a fourth dose will provide just marginal or short-lived protection against severe COVID-19.
The New England Journal of Medicine (NEJM) recently published a study from Israel that indicated that while a fourth dose for those over 60 had increased protection from infection and severe COVID-19, the vaccine's effectiveness against infection started to fade after several weeks.
A second study out of Israel published in the British Medical Journal (BMJ) found that while the vaccine offered additional protection against hospitalization and death for people 60 and older in the three weeks after a fourth shot, protection against infection decreased quickly.
The BMJ also published a Canadian study assessing the effectiveness of a fourth dose on long-term care residents in Ontario. While it found that the shot increased protection against infection and severe COVID-19 initially, the duration of that protection is still unknown.
Research suggests that the following groups do benefit from a fourth dose, including:
- High-risk or immunocompromised individuals
- Older people (60+)
- Residents in long-term care
- Other vulnerable groups
Conversely, we lack data that show a clear benefit to individuals under 60 getting the shot.
Some experts have said that almost everyone getting fourth doses as soon as possible, all at once to gain immunity for six to eight weeks.
A larger issue is that less than 50 percent of Canadians have gotten a third dose of the vaccine. It's also becoming increasingly critical to correctly time boosters to ensure robust immune protection against COVID-19 variants and subvariants, including the emerging BA.4 and BA.5.
Some Canadians may choose to get a fourth dose when it becomes available to them even if they will only be protected against infection for several weeks.
While the first two doses had significant influence on disease dynamics and the third was able to save many from falling severely ill with Omicron, the evolution of the virus and the vaccines could mean we'll need other solutions to help prevent transmission.
Couple Testing With Vaccines
If you are planning to travel in the near future or are just seeking some peace of mind, you may wish to pair COVID testing with updating your vaccinations.
If this is the case for you, we can administer COVID-19 tests, including Antigen Tests and RT-PCR tests at our two locations. We can also answer any questions you may have about Covid Certificates.