National Post (National Edition)
A clear path to easing lockdowns
As the first Canadians begin to receive the COVID-19 vaccine, a momentous milestone in the pandemic has been marked. Never before has a new vaccine technology — messenger RNA in this case — moved so quickly from laboratory to bedside in the midst of an outbreak. Miraculously, three different vaccine preparations are already being administered worldwide. That is a good thing. However, the parameters needed to ease societal restrictions during the long vaccine deployment will need to be redefined. Otherwise, confusion associated with roller-coaster lockdowns will reign, leading to frustration from both an economic and societal point of view. Many policy-makers previously opined that the restrictions and hardships currently endured by most Canadians would come to an end with the arrival of the vaccine. Others have cautioned that immunity of at least half, and perhaps even 80 per cent, of the population through infection or vaccination is necessary before restrictions can be lifted. Now that we have a vaccine, we believe that it might be possible to ease restrictions sooner.
We know for certain that over 500,000 Canadians have been diagnosed with COVID and that many more have been infected but not tested. They are essentially immunized by naturally acquired immunity, and are unlikely to transmit the infection to others in the near future. Correlates of complete protection are still unknown, and as expected with a respiratory virus, a small number of reinfections with COVID have been documented. We do not know yet how long immunity persists and whether it is more durable following natural infection or following vaccination. Even current blood tests do not allow us to definitively determine who is susceptible to infection or reinfection.
Following the summer lull that mirrors most respiratory virus activity, COVID has returned with a vengeance. Contrary to popular belief that this is because we lowered our guard, most temperate northern hemisphere locales have seen the same pattern and it seems likely that this second wave would have occurred whether or not mask wearing and other protective measures were in place over the summer. The occurrence of the second wave is largely not the consequence of renegade behaviour but of the seasonality of a respiratory virus, and increased indoor activity due to seasonal weather changes.
We know that the peak of an outbreak is passed when the daily deaths and hospital admissions are in decline. Appropriately, the vaccine is now being given to protect the most vulnerable — namely health-care workers who care for COVID patients, the elderly and those who work in long-term care facilities. As approximately 65 per cent of Canada's deaths during the first COVID-19 wave occurred in such facilities, this may prevent some deaths in the current wave and may abort a third wave in these facilities. (A caution is that we still do not know how well the vaccine will protect the most elderly or other vulnerable populations). The highly touted 95 per cent figure for vaccine efficacy applies only to healthy volunteers (mostly under age 55) — the original study group for the vaccine. The aim of vaccinating the most vulnerable is that the proportion that will need hospitalization or be seriously ill should decrease, thereby allowing our hospitals to function in providing much-needed care for other conditions.
As opposed to the number hospitalized, the press unfortunately continues to focus on the daily COVID-19 case rate, which is reflective of transmissibility among the general population — most of whom do not need hospitalization. Since the vaccine will likely only be widely available to the majority of the population after the peak of the current wave, the vaccine rollout in its current form will not reliably “flatten the curve” in the short term.
Who should receive the vaccine next after the residents and caregivers in long-term care is not without controversy. Should it be other people at risk of hospitalization with COVID (such as adults with hypertension, obesity, diabetes mellitus or over a certain age), people in contact with large numbers of other people in congregate settings (such as those who work in meat packing plants or warehouses with hundreds or employees) or those who may even be asymptomatic but are likely to spread COVID to others (such as young people living and working at ski resorts)? We are missing key information that would help to inform this decision. We know that vaccinated people do not seem to become ill when they get COVID but perhaps they still get asymptomatic or very mild infections and can spread COVID to others. Preliminary data for the AstraZeneca vaccine showed that it prevented only 27 per cent of asymptomatic infections, but this estimate may prove to be inaccurate and may differ for other COVID vaccines.
When, then, can the current onerous societal restrictions be lifted? Perhaps sooner rather than later, but it depends on the barometer we are using. If most of the high-risk population is immunized and if vaccine efficacy and safety match the preliminary data, we should be able to prevent most longterm morbidity and mortality if we vaccinate the groups at risk of highest morbidity and mortality. Once the number of hospitalizations goes down to a manageable threshold, the economic and social harms of continuing the restrictions outweigh the benefits, even if the number of non-hospitalized cases continues to wax and wane. Waiting for population immunity anywhere close to 50 per cent with vaccine and natural infection is many months away. Therefore, using total case counts as a barometer for when we can lift restrictions is not optimal as it is very much a function of how many people choose to get tested and does not reflect the true burden of the morbidity and mortality of the pandemic. As we enter the COVID-19 vaccine era, the management of societal expectations will require that public health authorities and politicians carefully enunciate and define a priori the barometers that will be used to ease lockdowns.
National Post
Neil V. Rau is an infectious diseases specialist and medical microbiologist at Halton Healthcare and Humber River
hospitals and an assistant professor at the University of Toronto. Nicole Le Saux is an infectious diseases specialist at the Children's Hospital of Eastern Ontario and a professor at the University of Ottawa. Joan Robinson is a pediatric infectious diseases specialist at Stollery Children's Hospital in Edmonton and a professor at the University of Alberta.
USING TOTAL CASE COUNTS AS A BAROMETER FOR WHEN WE CAN LIFT RESTRICTIONS
IS NOT OPTIMAL.