ABSTRACT
Background. During the early Covid-19 pandemic, we observed a close-to-full disappearance of the activity of 4 respiratory viruses (RSV, hMPV, influenza, and parainfluenza), followed by an off-season sequential re-emergence in 2021. Surprisingly, a striking similarity between the dynamics of pneumococcus-associated disease (PAD;namely community-acquired alveolar pneumonia [CAAP;often considered pneumococcal] and bacteremic-pneumococcal pneumonia [IPD-Pneumonia]), was also observed. In contrast, adenovirus and rhinovirus activities did not change during COVID-19. We examined the association between PAD and RSV, hMPV, influenza, and parainfluenza (PAD-viruses). Methods. Surveillance of CAAP and IPD-Pneumonia incidences and viral activity in children < 5 years was described in detail previously [Danino D. et al. Clin Infect Dis. 2022, https://doi.org/10.1093/cid/ciab1014]. We extended the observations until December 2021, to capture the sequential re-emergence of the 4 PAD-viruses. A hierarchical linear regression model was used to quantify the association between PAD-viruses (each virus individually and combined), adenovirus and PAD. After fitting the models, the contribution of each virus was estimated. Results. The Figure shows striking similarities in the dynamics of CAAP, IPD-Pneumonia, and PAD-viruses both before and during the COVID-19 pandemic. During the expected peak season (Oct 2020 - Apr 2021) PAD episodes were extremely low. However, off-season peaks were seen during May - Dec 2021. Overall, 78% and 25% of all CAAP and IPD-Pneumonia episodes, respectively, were attributable to these viruses in children < 5 (Table). In CAAP, cases were attributable to each of the 4 PAD-viruses individually throughout the first 5 years of life: RSV and hMPV combined contributed 80%, 63%, and 42% of all CAAP episodes in children aged < 1, 1, and 2-4 years, respectively. The respective figures for influenza and parainfluenza combined were 13%, 21%, and 22%. Only RSV significantly contributed to IPD-Pneumonia (19%). Adenovirus did not contribute to PAD episodes. Conclusion. Our model suggests an important causative association between RSV, hMPV, influenza, and parainfluenza viruses and CAAP, and between RSV and IPD-Pneumonia. (Figure Presented).
ABSTRACT
Background. Respiratory syncytial virus (RSV) and human metapneumovirus (hMPV) and to a lesser extent, parainfluenza and influenza viruses have been associated with pneumonia in young children. In contrast, adenovirus (AdV) and rhinovirus (RhV) are usually not associated with pneumonia. We aimed to evaluate the involvement of the four pneumonia associated viruses (grouped as PAV) in pediatric CAAP, before and during the COVID-19 pandemic. Methods. CAAP incidence and viral activity surveillance in southern Israel in children < 5y and virological detection methods were described previously (Danino. CID 2022, https://doi.org/10.1093/cid/ciab1014). We reviewed the period of Jan 2016 - Mar 2022. Most cases of COVID-19 in children < 5y occurred during Dec 2021 - Mar 2022 (Figure 1);Over 95% of children admitted for respiratory disease were tested for COVID-19 (PCR). Since AdV and RhV activity was previously not associated with CAAP and tended to be equally involved in mixed and single infections, the current analysis was done for the four PAV only. Results. CAAP incidence dynamics closely resembled the four PAV (grouped) activity dynamics (Figure 2A, 2B) with very low activity during the expected peak in winter 2020-2021, but with an off-season resurgence from spring 2021. Even though most CAAP episodes during the pandemic coincided with peak COVID-19 rates, only 9 CAAP episodes were COVID-19 positive (7 in 2022, of which 5 were RSV positive). Out of 3,430 CAAP episodes 55% were tested for PAV, of which 61% were positive, with similar rates before and during the pandemic. RSV was the most common involved virus, followed by hMPV. The virus distribution in CAAP during the entire period reflected their activity in the community (Figure 2C). Unlike pre-pandemic years where all four PAV appeared almost simultaneously, in 2021 PAV resurged sequentially, resulting in successive involvement in CAAP episodes, suggesting a causative association. Conclusion. 1. SARS-CoV-2 was only rarely involved in CAAP in young children. 2. PAV were involved in 61% of CAAP episodes in children < 5y with predominance of RSV and hMPV. 3. The atypical dynamics imposed by the COVID-19 pandemic suggests a causative association between PAV and CAAP. (Figure Presented).