Table 4.
Impact of lifting of COVID-19 restrictions on disease epidemiology.
| Study | Population | Country | Changes in Disease Epidemiology |
|---|---|---|---|
| Pneumococcal pneumonia | |||
| Casanova58 | General population (Population-level data) | Switzerland | From February 2020 (n = 139) to April 2020 (n = 22), a drastic decline of IPD isolates was observed. Numbers remained low from April 2020–February 2021 (n = 19). COVID-19 measures were loosened by the Swiss government on March 1, 2021, and numbers started to increase from March 2021 (n = 31) to May 2021 (n = 49). June 2021, the same number of IPD isolates (n = 47) as for June 2019, 2018, and 2017, was observed. |
| Perniciaro59 | General population (Population-level data) | Germany | IPD incidence decreased sharply in the second quarter of 2020 and returned to baseline levels in the beginning of the third quarter of 2021. |
| RSV | |||
| Foley60 | Children (n = 917) | Australia | COVID-19 public health measures contributed to a shift in transmission of respiratory viruses, including a delay in the expected RSV season. A summer peak of RSV-positive admissions, 2.5 times the magnitude of the previous mid-winter peak, was observed. |
| Halabi61 | Children and adolescents (n = 143) | US | The overall number of RSV cases decreased in 2020 to 2021 compared with both previous seasons with inter-seasonal resurgence. Despite lack of known risk factors, a higher proportion of children had severe disease in the 2020 to 2021 season. |
| Hussain62 | Children (n = 2,922) | UK | In 2020 to 2021 there was a drop in bronchiolitis cases, and no RSV cases were identified. The most likely reason was that of NPIs resulting in reduced transmission of viruses. In Wales, a reemergence of RSV bronchiolitis cases at a rapid rate that is out of sync to the usual seasonal pattern was observed. |
| van Summeren63 | General population (Population-level data) | Europe | RSV epidemics were only observed in Europe during the 2020–2021 season in France and Iceland, countries that had a policy of keeping their primary schools and daycare facilities open. In the Netherlands, the RSV epidemic started 19 weeks after schools were reopened, suggesting that school closures had an impact on RSV activity. |
| Norovirus | |||
| O’Reilly64 | General population (Population-level data) | England | During the first lockdown until the school reopening stage, the rate of infection for norovirus is sufficiently low that new infections are rare. The third lockdown period corresponds to a reduction in contacts (from 6.61 to 3.47) and the rate of infection falls to low levels again, until schools are reopened. Subsequently, model scenarios predicted a rise in the rate of infection and a resurgence of norovirus in the community resulting in an annual incidence of cases up to 2 times higher than simulations prior to 2020. |
| Multiple diseases | |||
| Baker65 | General population (Population-level data) | US | Following NPIs due to COVID-19, a decline in RSV prevalence was observed beyond mean seasonal levels The 2019–2020 influenza season was more severe than average, with a relative increase in prevalence prior to March 2020; however, there was a decline to below average levels across almost all US states. Models identified that longer periods of NPIs, and subsequently reduce transmission, lead to greater increase in susceptibility and larger resulting outbreaks. |
| Redlberger-Fritz66 | General population (n = 25,491)* | Austria | A rapid and statistically significant reduction of cumulative cases of influenza viruses, RSV, human Metapneumovirus and Rhinoviruses within short time after the lockdown in March 2020, compared to previous seasons. A reemergence of rhinovirus infections was observed after lifting of lockdown measures. |
| Wan67 | Hospitalized patients (n = 42,558)** | Singapore | Implementation of NPIs pre-lockdown was associated with a reduction of influenza and RSV and a reduction of enterovirus/rhinovirus and adenovirus was only observed when lockdown was instated. During reopening, low levels of all viruses were sustained for approximately 13 weeks, but a reemergence of enterovirus/rhinovirus occurred in early September and a less pronounced rebound of adenovirus in mid-October. |
*Number of nasopharyngeal swabs samples.
**Number of specimens from patients with respiratory symptoms, sent for routine diagnostic purposes.
Abbreviations: COVID-19 = coronavirus disease 2019; IPD = invasive pneumococcal disease; NPI = non-pharmacological intervention; RSV = respiratory syncytial virus; UK = United Kingdom; US = United States.