29 November 2022
When confronted with the COVID-19 pandemic, a number of countries such as China, New Zealand and Australia implemented the Zero-COVID approach where strict border control and intense response to local transmission events ensured viral elimination from the country. While Zero-COVID has proven to be an effective strategy, it results in a difficult problem.
It is essential to develop public health strategies that limit the risk of a massive wave of hospitalisations when Zero-COVID ends in these regions. Vaccination is a key ingredient for a successful exit. However, increasing vaccine coverage may be difficult if the population is reluctant to get vaccinated. Therefore, complementary approaches such as test-and-treat with antiviral drugs may have to be considered. For example with Nirmatrelvir/ritonavir (brand name Paxlovid), which is an antiviral drug given orally for five consecutive days. It has been shown to reduce the risk of COVID-19-related hospitalisation and death in patients with mild-to-moderate COVID-19 and who are at high risk for progression.
In November 2022, a new RECOVER paper was published titled ‘Modelling the end of a Zero-COVID strategy using nirmatrelvir/ritonavir, vaccination and NPIs in Wallis and Futuna’. The aim of the study was to investigate how targeted use of nirmatrelvir/ritonavir can complement vaccination and non-pharmaceutical interventions (NPIs), and mitigate the epidemic rebound expected when Zero-COVID ends.
Findings
The epidemic is expected to start 13–20 days after reopening the area for travel. For medium transmission intensity, 134 hospital admissions are expected within 3 months, with no pharmaceutical measures. In the baseline scenario, admissions are reduced by 11%–21% if 50% of the target group receive treatment, with maximum impact when combined with NPIs and vaccination. The number of hospitalisations averted per patient treated is maximum when 65+ year olds in high comorbidity risk groups are targeted. Modelling suggests that test and treat may contribute to the mitigation of epidemic rebounds at the end of Zero-COVID, particularly in populations with low immunity and high levels of comorbidities.