People infected with COVID-19 before getting their third dose of the vaccine should wait before making an appointment until the scientific data on the matter becomes clearer, experts say.
This is a scenario that many Quebecers are likely to face, at a time when the Omicron variant is spreading at a lightning speed and the provincial vaccination campaign is not moving fast enough to the liking of some.
“Unfortunately, the scientific data are not clear on this,” summed up Dr. Cécile Tremblay of the CHUM in an email. We have to wait for the results of studies comparing the immune response of these people against the third dose. In the meantime, it is better to wait. ”
Doctor Caroline Quach-Thanh, of the CHU Sainte-Justine, refers to a document from the National Institute of Public Health of Quebec (INSPQ) which, dated December 16, underlined that “people having been infected by SARS -CoV-2 constitute a special case ”.
A SARS-CoV-2 infection provides “robust” protection, the document says, and this protection may be more durable than that resulting from vaccination, since the antibodies persist longer.
Vaccination increases the protection acquired by the infection, “but the benefit in absolute terms is modest”, underlines the INSPQ. A booster dose in a person who has already received two doses of the vaccine and who had a confirmed infection would therefore be “of little use”, it adds.
Adverse effects in some could not be ruled out either, the document says.
“The administration of a third dose of vaccine is therefore not necessary for these people, but could be administered if the person requests it,” explains the INSPQ. An interval of 3 months between the last dose or infection and the booster dose would be ideal, with a minimum interval of 8 weeks. “
There are therefore “still uncertainties on the benefits and risks associated with the administration of a booster dose (3rd dose in people with a history of SARS-CoV-2 infection) in people previously infected”, concludes the INSPQ.