Protection of hybrid immunity against SARS-CoV-2 reinfection and severe COVID-19 during periods of Omicron variant predominance in Mexico

Abstract

BackgroundWith the widespread transmission of the Omicron SARS-CoV-2 variant, reinfections have become increasingly common. Here, we explored the role of immunity, primary infection severity, and variant predominance in the risk of reinfection and severe COVID-19 during Omicron predominance in Mexico.MethodsWe analyzed reinfections in Mexico in individuals with a primary infection separated by at least 90 days from reinfection using a national surveillance registry of SARS-CoV-2 cases from March 3rd, 2020, to August 13th, 2022. Immunity-generating events included primary infection, partial or complete vaccination, and booster vaccines. Reinfections were matched by age and sex with controls with primary SARS-CoV-2 infection and negative RT-PCR or antigen test at least 90 days after primary infection to explore reinfection and severe disease risk factors. We also compared the protective efficacy of heterologous and homologous vaccine boosters against reinfection.ResultsWe detected 231,202 SARS-CoV-2 reinfections in Mexico, most occurring in unvaccinated individuals (41.55%). Over 207,623 reinfections occurred during periods of Omicron (89.8%), BA.1 (36.74%), and BA.5 (33.67%) subvariant predominance and a case-fatality rate of 0.22%. Vaccination protected against reinfection, without significant influence of the order of immunity-generating events and provided >90% protection against severe reinfections. Heterologous booster schedules were associated with ~11% and ~ 54% lower risk for reinfection and reinfection-associated severe COVID-19, respectively, modified by time-elapsed since the last immunity-generating event, when compared against complete primary schedules.ConclusionSARS-CoV-2 reinfections increased during Omicron predominance. Hybrid immunity provides protection against reinfection and associated severe COVID-19, with potential benefit from heterologous booster schedules.

COVID-19 reinfections in Mexico City: implications for public health

“…Boosters also play a vital role in delaying reinfections, even for those with previous breakthrough cases. Our findings align with recent studies on hybrid immunity ( 20 ) and emphasize the importance of regular booster shots for effective virus control; as they have a better effect of delaying symptomatic infection than a primary series alone. However, given the complexity of infection risk, determining an optimal vaccination schedule based solely on these findings is challenging.…”

Factors associated with childhood non-vaccination against COVID-19 in Canada: A national survey analysis

“…Among individual KABs, the strongest association with non-vaccination was observed in respondents who disagreed with the statement ‘My child needs to be vaccinated against COVID-19 even after infection.’ This aligns with prior research indicating a decreased willingness to vaccinate post-COVID-19 recovery [45] . Despite evidence showing that hybrid immunity—resulting from both infection and vaccination—substantially lowers the risk of severe reinfection compared to immunity from previous infection alone [46] , [47] , only 63 % of our respondents acknowledged the importance of vaccination post-infection. By March 2023, a significant portion of the Canadian population had experienced COVID-19 infection [48] .…”

A mini review of reinfection with the SARS‐CoV‐2 Omicron variant

“…There was a significant increase in the SARS‐CoV‐2 reinfection rate before and during the Omicron variant period (0.8% vs. 4.3%; p < 0.001) 16 . Another study conducted in Mexico identified a reinfection rate of 3.1% during the Omicron predominance period 17 . According to the latest national surveillance data in Singapore, the incidence of Omicron BA.4 or BA.5 was 7.7−78.3/million PD, while the incidence of Omicron XBB reinfection ranged from 509 to 1854/million PD, depending on the individual's vaccination status and previous infected lineage (Table 1).…”

“… 16 Another study conducted in Mexico identified a reinfection rate of 3.1% during the Omicron predominance period. 17 According to the latest national surveillance data in Singapore, the incidence of Omicron BA.4 or BA.5 was 7.7−78.3/million PD, while the incidence of Omicron XBB reinfection ranged from 509 to 1854/million PD, depending on the individual's vaccination status and previous infected lineage (Table 1 ). 18 It is worth noting that Ciuffreda's study did not report the specific incidence, but found that BA.5 had the highest reinfection rate compared to other lineages, including BA.1, BA.2, and BA.4.…”