TY - JOUR
T1 - Increased transmissibility of SARS-CoV-2 alpha variant (B.1.1.7) in children
T2 - three large primary school outbreaks revealed by whole genome sequencing in the Netherlands
AU - Gorgels, Koen M F
AU - van Alphen, Lieke B
AU - van der Veer, Brian M J W
AU - Hackert, Volker H
AU - Hensels, Audrey Y J
AU - Heijer, Casper D J den
AU - Dingemans, Jozef
AU - Savelkoul, Paul H M
AU - Hoebe, Christian J P A
N1 - © 2022. The Author(s).
PY - 2022/8/29
Y1 - 2022/8/29
N2 - BACKGROUND: Variant of concern (VOC) SARS-CoV-2 alpha variant (B.1.1.7) was the dominant strain in the Netherlands between March 2021-June 2021. We describe three primary school outbreaks due to the alpha variant using whole genome sequencing with evidence of large-scale transmission among children, teachers and their household contacts.METHOD: All outbreaks described were investigated by the South Limburg Public Health Service, the Netherlands. A case was defined as an individual with a real-time polymerase chain reaction test or antigen test positive for SARS-CoV-2. Whole genome sequencing was performed on random samples from at least one child and one teacher of each affected class.RESULTS: Peak attack rates in classes were 53%, 33% and 39%, respectively. Specific genotypes were identified for each school across a majority of affected classes. Attack rates were high among staff members, likely to promote staff-to-children transmission. Cases in some classes were limited to children, indicating child-to-child transmission. At 39%, the secondary attack rate (SAR) in household contacts of infected children was remarkably high, similar to SAR in household contacts of staff members (42%). SAR of household contacts of asymptomatic children was only 9%.CONCLUSION: Our findings suggest increased transmissibility of the alpha variant in children compared to preceding non-VOC variants, consistent with a substantial rise in the incidence of cases observed in primary schools and children aged 5-12 since the alpha variant became dominant in March 2021. Lack of mandatory masking, insufficient ventilation and lack of physical distancing also probably contributed to the school outbreaks. The rise of the delta variant (B.1.617.2) since July 2021 which is estimated to be 55% more transmissible than the alpha variant, provides additional urgency to adequate infection prevention in school settings.
AB - BACKGROUND: Variant of concern (VOC) SARS-CoV-2 alpha variant (B.1.1.7) was the dominant strain in the Netherlands between March 2021-June 2021. We describe three primary school outbreaks due to the alpha variant using whole genome sequencing with evidence of large-scale transmission among children, teachers and their household contacts.METHOD: All outbreaks described were investigated by the South Limburg Public Health Service, the Netherlands. A case was defined as an individual with a real-time polymerase chain reaction test or antigen test positive for SARS-CoV-2. Whole genome sequencing was performed on random samples from at least one child and one teacher of each affected class.RESULTS: Peak attack rates in classes were 53%, 33% and 39%, respectively. Specific genotypes were identified for each school across a majority of affected classes. Attack rates were high among staff members, likely to promote staff-to-children transmission. Cases in some classes were limited to children, indicating child-to-child transmission. At 39%, the secondary attack rate (SAR) in household contacts of infected children was remarkably high, similar to SAR in household contacts of staff members (42%). SAR of household contacts of asymptomatic children was only 9%.CONCLUSION: Our findings suggest increased transmissibility of the alpha variant in children compared to preceding non-VOC variants, consistent with a substantial rise in the incidence of cases observed in primary schools and children aged 5-12 since the alpha variant became dominant in March 2021. Lack of mandatory masking, insufficient ventilation and lack of physical distancing also probably contributed to the school outbreaks. The rise of the delta variant (B.1.617.2) since July 2021 which is estimated to be 55% more transmissible than the alpha variant, provides additional urgency to adequate infection prevention in school settings.
KW - COVID-19/epidemiology
KW - Disease Outbreaks
KW - Humans
KW - Netherlands/epidemiology
KW - SARS-CoV-2/genetics
KW - Schools
KW - Whole Genome Sequencing
U2 - 10.1186/s12879-022-07623-9
DO - 10.1186/s12879-022-07623-9
M3 - Article
C2 - 36038845
SN - 1471-2334
VL - 22
JO - BMC Infectious Diseases
JF - BMC Infectious Diseases
IS - 1
M1 - 713
ER -