Available online 10 November 2023, 105617

This manuscript reports on the phylogenetic and clinical changes of the most commonly detected enterovirus types before and after the pandemic lockdown measures in the Netherlands.

The public health measures which were instated to prevent SARS-CoV-2 transmission, also reduced transmission of non-SARS viruses, as virus circulation diminished strongly during these months. Most viruses, including enteroviruses, returned after lockdown measures were lifted. However, circulation of some viruses may be affected long-term. For Influenza it was shown that the pandemic lockdown measures led to disappearance of the Yamagata/B lineage, and some clades of Influenza A/H3N2 have not been detected since march 2020. It is now thought that the collective public health measures have led to a “funnel effect” for Influenza viruses.

A potential “funnel effect” may be observable for other viruses as well, but this has not yet been investigated. Our study investigates if the enteroviruses which reappeared after the lockdown were different form the ones detected before the lockdown.

Our data shows that a reduction in genetic variability occurred during the lockdown, and many sequences after the lockdown show very high homology. Our study is too small and too limited in geographical area to prove a funnel effect for enteroviruses. The data nevertheless does indicate that changes have occurred, and these changes may become clinically relevant.

Public health measures aimed at controlling transmission of SARS-CoV-2, otherwise known as “lockdown” measures, had profound effects on circulation of non-SARS viruses, many of which decreased to very low levels. The interrupted transmission of these viruses may have lasting effects. Some of the influenza clades seem to have disappeared during this period, a phenomenon which is described as a “funnel effect”. It is currently unknown if the lockdown measures had any effect on the diversity of circulating viruses, other than influenza. Enteroviruses are especially interesting in this context, as the clinical presentation of an infection with a particular enterovirus-type may be clade-dependent.

Enteroviruses were detected in clinical materials using a 5’UTR-based detection PCR, and partial VP-1 sequences were obtained, using methods described before. All samples with EV detections from a large part of the Netherlands were included in the study. The samples originated from general practitioners, general hospitals, university hospitals and public health offices.

Five EV-genotypes circulated in significant numbers before and after the lockdown, EV-D68, E-11, CV-A6, CV-B5 and CV-A2. All five genotypes showed decreased genetic diversity after the lockdown, and four indicate a significant number of sequences clustering together with a very high sequence homology. Moreover, children with E-11 and CV-B5 detections were significantly older after the lockdown than before.

The reduced enterovirus transmission in the Netherlands during the pandemic, seems to have led to a decrease in genetic diversity in the five most commonly detected enterovirus serotypes

Enteroviruses

epidemiology

phylogenetic analysis

post-pandemic changes

funnel effect

© 2023 The Author(s). Published by Elsevier B.V.