Don’t let your guard down

Re: No more holding back on vaccine for second shot in Manitoba, Dec. 31; and Appointments for second dose of COVID-19 vaccine cancelled in Quebec, Jan. 4

The release of the COVID-19 vaccines in under one year is nothing short of a miracle and our main hope for restoring the physical, mental and socioeconomic health of our country.

B. C. and other health authorities’ decision to delay the second dose, so that more people will get earlier access, is unsupported by research. The 95 per cent efficacy is based on two doses given three to four weeks apart, which is Health Canada’s recommendation. The published study for the Pfizer vaccine reports the efficacy was only 52 per cent after one dose ( New England Journal of Medicine — December 2020) and the unpublished data from Moderna showed 69 per cent efficacy (CDC) after the first dose. This is very different than the quoted “upwards of 80 per cent efficacy after one dose.” We are also in uncharted waters about whether delaying the second dose, beyond the fourth week, may lower its overall efficacy.

People receiving one dose of vaccine may become complacent, thinking they are “over 80 per cent protected” against COVID- 19. It behooves everyone, especially those working and in contact with elderly and other vulnerable people, to continue to practice the strictest precautions with distancing, masks and handwashing, until at least one week after they receive their second dose of vaccine.

Ted Rosenberg MD MSC. FRCP( C), Clinical Assistant Professor University of British Columbia