Increased Incidence of Invasive Pneumococcal Disease among Children after COVID-19 Pandemic, England : The Pediatric Infectious Disease Journal

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Increased Incidence of Invasive Pneumococcal Disease among Children after COVID-19 Pandemic, England

The Pediatric Infectious Disease Journal: December 2022 - Volume 41 - Issue 12 - p 988
doi: 10.1097/INF.0000000000003725
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Bertran M, Amin-Chowdhury Z, Sheppard CL, et al. Emerg Infect Dis 2022;28:1669–1672

The Coronavirus disease 2019 (COVID-19) pandemic and its associated lockdowns, social isolation and other interventions led to large declines in respiratory infections, including invasive pneumococcal disease (IPD). In England, IPD cases declined by 30% after the first lockdown in March 2020 and remained low during the subsequent winter until February 2021, when cases increased by 8% above the 3-year pre-pandemic mean incidence for February. As the country ended its third national lockdown in March 2021, after the emergence of the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Alpha variant, IPD cases started to gradually increase. By June 2021, case numbers remained 25% lower than prepandemic levels, but a proportionately higher increase in cases among children <15 years of age was observed. IPD trends during July–December 2021, after England removed all COVID-19 control measures on July 19, 2021 are described.

IPD cases during July–December 2021 were compared to July–December 2020 and July–December in 3 pre-pandemic years (2017–2019) by using national enhanced surveillance data for England. During July–December 2021, a total of 1632 IPD cases were reported to the United Kingdom Health Security Agency, compared with a mean of 2403 during July–December of 3 pre-pandemic years, 2017-2019. Among children <15 years of age, the number of IPD cases and incidence (cases per 100,000 children) declined by 50% (n = 71) during July–December 2020 but gradually increased in February 2021 and remained above the 3-year pre-pandemic mean of 145 cases (incidence 1.43, 95% CI: 1.21–1.68) during July–December 2021 (n = 200; 1.96, 95% CI: 1.70–2.25). Case rates rose earlier in younger age groups among whom incidence was highest during this period: 10.63 (95% CI: 8.19–13.58) among <1-year olds; 3.22 (95% CI: 2.57–3.98) among 1–4 year-olds; 1.02 (95% CI: 0.71–1.41) among 5–9-year-olds; and 0.44 (95% CI: 0.24–0.72) among 10–14 year-olds. Cases also increased (n = 1432) among persons >15 years old during February–December 2021, but the incidence during July–December 2021 remained lower (2.60, 95% CI: 2.47–2.74) than the prepandemic mean during July–December in 2017–2019 (4.14, 95% CI: 3.97–4.32).

Age distribution of childhood IPD cases resembled the prepandemic period (p = 0.08): 32% of cases were among <1-year-olds, 42.5% among 1–4 year-olds, 18% among 5–9 year-olds, and 7.5% among 10–14 year-olds. Of 172 (86%) pneumococcal isolates serotyped, no difference in serotype distribution between years or within age groups was noted. The most frequent serotypes among childhood cases remained similar in 2021 to those in pre-pandemic years.

More IPD cases in 2021 involved bacteremia (50/125, 40%) compared with the prepandemic period (105/422, 25%). The proportion of cases with meningitis (22%), pneumonia (31%) and other clinical manifestations (7%) were not substantially different. The prepandemic and postpandemic 30-day fatality rates were also similar (5% vs. 4%, p = 0.6)

Comment: After lifting COVID-19 social restrictions, England experienced an increase in childhood IPD cases that exceeded prepandemic levels. England’s pandemic social restrictions led to large declines in many infectious diseases, including IPD. Reduced social contact and exposure to respiratory pathogens have led to concerns of immunity debt and risk for higher infection rates as restrictions are lifted globally. Immunity debt is typified in the emergence of respiratory viruses outside their typical season, as observed with the respiratory syncytial virus. Of note, respiratory virus infections that usually peak in winter (eg, influenza and rhinovirus) remained low during winter 2021–2022.

In the United Kingdom, the 13-valent pneumococcal conjugate vaccine (PCV13) vaccination schedule for infants born after January 1, 2020, was changed from a 2 + 1 schedule (8 weeks, 16 weeks and 1 year) that had been in place since 2010 to a reduced 1 + 1 schedule (12 weeks and 1 year). This change was made on the basis that most protection is through the indirect herd or population protection offered by preventing carriage among toddlers, thus interrupting transmission to others. However, the program relies on maintaining high vaccine coverage in infants to provide adequate population protection.

In England, PCV13 coverage data for the 12-month dose were not available 2020–2021 during this study, but uptake of other childhood vaccines was lower after the pandemic started and improved during August–December 2021. Because of the COVID-19 pandemic restrictions, evaluation of the effect of the 1 + 1 schedule is not yet possible. Maintaining high PCV13 uptake is critical for ongoing population protection.

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