The potential impact of previous exposure to SARS or MERS on control of the COVID-19 pandemic.

The Severe Acute Respiratory Syndrome coronavirus 2 (SARS-CoV-2) is believed to share similar characteristics with SARS in 2003 and Mediterranean East Respiratory Syndrome (MERS) in 2012. We hypothesized that countries with previous exposure to SARS and MERS were significantly more likely to have fewer cases and deaths from coronavirus disease 2019 (COVID-19). We retrieved the incidence of COVID-19 per 100,000 population within 30 days since the first confirmed case was reported from the 2019 Novel COVID-19 data repository by the Johns Hopkins Centre for Systems Science and Engineering for 94 countries. The association between previous exposure to SARS and/or MERS and the 30-day COVID-19 incidence rate was examined by multivariable linear regression analysis, whilst controlling for potential confounders including the INFORM COVID-19 Risk Index, Testing Policies, Democracy Index, Scientific Citation Index, Gross Domestic Product (GDP), Human Development Index (HDI) and the population density of each country. We found that countries with previous exposure to SARS and/or MERS epidemics were significantly more likely to have lower incidence of COVID-19 (β coefficient - 225.6, 95% C.I. - 415.8,- 35.4, p = 0.021). However, countries being classified as having "full democracy" using Democracy Index had higher incidence of COVID-19 (reference: authoritarian regime; β coefficient 425.0, 95% C.I. 98.0, 752.0, p = 0.011). This implies that previous exposure to global epidemics and Democracy Index for a country are associated its performance in response to COVID-19. We recommend future studies should evaluate the impact of various pandemic control strategies at individual, community, and policy levels on mitigation of the disease.