On the increasing role of older adolescents and younger adults during the SARS-CoV-2 epidemic in Mexico

Stern, Dalia; Lajous, Martin; De la Rosa, Blanca; Goldstein, Edward

BACKGROUND: During the first months of the SARS-CoV-2 pandemic, Mexico implemented a national lockdown followed by post-lockdown mitigation. METHODS: We used daily number of SARS-CoV-2-confirmed hospitalizations (by date of symptom onset) to assess the changes in the incidence of individuals between the age of 10–59 years during the epidemic in Mexico. For each age group g, we computed the proportion E(g) of individuals in that age group among all cases aged 10–59y during the early lockdown period (April 20–May 3, 2020), and the corresponding proportion L(g) during the late lockdown period (May 18–31, 2020) and post-lockdown mitigation (June 15–28, 2020). For each later period (late lockdown or post-lockdown), we computed the proportion ratios relative to the early lockdown period PR(g)=L(g)/E(g). For each pair of age groups g1,g2, PR(g1)> PR(g2) is interpreted as a relative increase in SARS-CoV-2 infections in the age group g1 compared to g2 for the late lockdown and post-lockdown periods vs. the early lockdown period. RESULTS: For the late lockdown period, the highest PR estimates belong to persons aged 15–19y (PR=1.69(95%CI(1.05, 2.72))) and 20–24y (PR=1.43(1.10,1.86)). For the post-lockdown period, the highest PR estimates were also in age groups 15–19y (PR=2.05(1.30, 3.24)) and 20–24y (PR=1.49(1.15,1.93)). These estimates were higher in persons 15–24y compared to those ≥30y. CONCLUSIONS: Our results suggest that adolescents and younger adults had an increased relative incidence during late lockdown and the post-lockdown mitigation periods. The role of these age groups during the epidemic should be considered when implementing future pandemic response efforts.