The weekly retrospective gives a summary of trends in acute respiratory infections, including COVID-19 and influenza (influenza virus) and respiratory syncytial virus (RSV).
Trends of the week
COVID-19: Decrease in the number of cases and the positivity rate of COVID-19.
Respiratory syncytial virus (RSV): Decrease in the number of RSV cases.
Influenza: Slight increase in the number of influenza cases.
COVID-19 / SARS-CoV-2
From 25 to 31 December 2023 (week 52), the number of people testing positive for SARS-CoV-2 dropped to 338 cases, compared to 686 cases the previous week (-51%).
The positivity rate fell to 20% compared to 26% the previous week.
These indicators suggest that the circulation of SARS-CoV-2 has decreased, which is probably linked to departures during the end-of-year holidays. A similar drop was also observed in 2022 during the end-of-year holidays.
The latest sequencing data available for weeks 48-50 show a preponderance of the JN.1 variant (60.9%) (95% CI 52.0-69.8%) followed by the BA.2.86 variant (11.3%) (95% CI: 5.5-17.1%) and the XBB.1.9 variant (10.4%) (95% CI: 4.9-16.2%) [1]. It should be noted that the JN.1 variant is a descendant of the BA.2.86 variant with an additional mutation on its spike protein.
Influenza
For the week of 25 to 31 December 2023 (week 52), the number of influenza cases reported by laboratories decreased to 332 cases from 375 cases in the previous week, a decrease of 16% compared to the previous week.
These data largely overlap with LNS sentinel surveillance, which indicates high circulation of the influenza virus, followed by SARS-CoV-2.
Respiratory syncytial virus (RSV)
For the week of 25 to 31 December 2023 (week 52), the number of respiratory syncytial virus (RSV)-positive individuals reported by laboratories dropped to 77 cases, compared with 141 the previous week, presenting an increase of 45%.
[1] https://lns.lu/publications/