Variants of the virus causing COVID-19 account for a large part of the resurgence of infections in many OECD countries since the latter part of 2020. By relating country-level daily reproduction numbers for OECD countries to several potential explanatory factors, this column shows that vaccination has been very effective at curbing COVID-19 infections and that a quick vaccine rollout can substitute for lockdown policies at much lower costs to the economy. However, policymakers should be aware that failure to vaccinate a sufficient share of the population could lead to a resurgence of the virus in the winter.
Variants of the virus causing COVID-19, notably the so-called UK or Alpha variant, have accounted for a large part of the resurgence of infections in many OECD countries since the latter part of 2020. Seasonal effects also drive fluctuations in virus incidence. More recently, vaccination has been very effective at curbing COVID-19 infections, substituting for lockdown policies at much lower costs to the economy (Gollier 2021). These are among the main findings of our recent work (Turner et al. 2021).
We relate country-level daily reproduction numbers for OECD countries to several potential explanatory factors, including containment policies, public health policies, seasonal conditions, the prevalence of variants, vaccination rates as well as proxies for spontaneous behavioural changes and natural immunity, all at once within the same framework. It also relates containment policies to the OECD weekly GDP tracker to study their effects on economic activity.
Some new variants of the virus are estimated to be able to boost the effective reproduction number by up to 50%. Seasonal effects are also found to increase the effective reproduction number in autumn/winter, in some countries by up to 25% relative to summer. The rapidity of these adverse shocks represent a major challenge to policymakers because they can coincide and take full effect over a matter of a few months. The two effects together can potentially boost reproduction numbers by up to 90%.
Thankfully, vaccination is found to powerfully reduce the spread of the virus. The estimated effects can be stated in intervention-equivalent terms (see Figure 1). Fully vaccinating…
- 7% of the population is equivalent to either complete school closure, requiring people not to leave the house with minimal exceptions, or banning all public gatherings;
- 15% of the population is equivalent to closing down all but essential workplaces;
- 20% of the population is equivalent to closing down all but essential workplaces as well as public transport;
- 50% of the population is equivalent to simultaneously applying all of the above restrictions as well as closing all international borders.