Introduction
Acute lower respiratory infections (ALRIs) are the main cause of illness
and hospitalization in children, and their most frequent etiology is
viral (1). During the COVID-19 pandemic, a decrease in pediatric visits
for respiratory causes was observed (2,3), probably because the
nonpharmacological mitigation measures used to face the pandemic altered
the circulation of the most common respiratory viruses.
However, many of the reports refer to a specific disease (bronchiolitis)
or to a particular virus (respiratory syncytial virus (RSV) and
influenza), include data from one or a few centers, or refer to
hospitalized patients (4,5,6). In contrast, there is little information
on the magnitude of this phenomenon in larger populations, especially in
relation to less seriously affected patients, who tend to be the
majority in the case of ALRIs.
Unfortunately, recording the reasons for health facility visit due to
ALRIs can be confusing (7). Despite the different coding systems used,
there is still difficulty in identifying ALRI-related visits (8). We
recently developed an algorithm that showed acceptable precision in the
identification of ALRI-related visits in electronic health records,
based not only on the reasons for consultation or identified diseases
but also on terms used by professionals in the text of the registry (9).
The public health system of the City of Buenos Aires has electronic
health records for ambulatory care areas before the pandemic, allowing a
precise evaluation of the impact of the pandemic on outpatient visits
for different causes in a large urban population.
Our objective was to evaluate the impact of the COVID-19 pandemic on
outpatient visits for acute respiratory infections in the city of Buenos
Aires.
Methods
This was an observational study that included all visits at health
facilities of the public health system of the City of Buenos Aires
(Gobierno de la Ciudad de Buenos Aires - GCABA) for children under 2
years of age, registered in the GCABA electronic health records, between
January 1, 2018, and December 31, 2022. The visits occurred at one of
the hospitals or primary care centers of the system (10).
To identify the visits in the GCABA health database, a validated
algorithm was (9).
The total number of visits and ALRIs-related visits and their
distribution throughout the study period, by year and by season (cold
months - autumn/winter: April, May, June, July, August and September -,
and warm months - spring/summer: October, November, December, January,
February and March) were evaluated.
The proportion of ALRIs-related visits was calculated (percentage with
95% CI). The proportion of ALRIs-related visits was compared between
different years (chi square for trend) and seasons (chi square). The
analysis was carried out using IBM-SSPS Statistics 22.0.
Data were conveniently anonymized. Approval by the Institutional Ethics
Committee was requested and obtained
(GCABA public research registry
number 7141/2022).
Results
In the period under study, 704,426 outpatient visits were registered
for children under 2 years of age in hospitals and primary care centers
of the GCABA. The average age of the patients was 0.8 ± 0.5 months, and
48% were male.
Of the total number of visits, 51,975 (7.38%; 95% CI 7.32-7.44) were
ALRIs-related.
The total number of visits, particularly those ALRIs-related, decreased
significantly during 2020 (Table 1).
In general, the proportion of ALRIs-related visits was significantly
higher in cold months than in warm months (9.8% vs. 5.5%; OR: 1.76
95% CI: 1.73-1.79; p <0.001). This distribution was clearly
observed before (2018, 2019) and after the pandemic (2022); during 2020,
it was reversed (more ALRI in warm months), and in 2021, no difference
was observed (Table 2).
A peak of ALRI-related visits occurred in the cold-month period in the
prepandemic years (2018-2019); there was no peak in 2020; and the peak
was delayed in 2021, with a recovery of prepandemic seasonality in 2022
(Figure 1).
Visits for ALRIs decreased after the institution of mobility
restrictions (March 2020) and increased again when the restrictions
decreased, in particular with the return to full school attendance (July
2021) (Figure 1).
Discussion
In countries with a temperate climate, ALRIs usually have a seasonal
pattern with an increase in cold months, following the circulation of
the main viruses responsible for such infections (RSV and influenza
virus); this pattern is observed both in the Northern Hemisphere and in
the Southern Hemisphere (11,12). In our study, in 2018 and 2019, we
verified this pattern in the city of Buenos Aires, with cases of ALRI
appearing in the cold months and peaking in June, the beginning of the
southern winter.
During the first year of the COVID-19 pandemic, a drastic decrease was
observed in health visits in general, and in visits for respiratory
infections in particular, for the pediatric population around the world
(13,14). This decrease was fundamentally attributed to the
nonpharmacological mitigation measures that adopted to reduce the risk
of SARS-CoV-2 infection: the use of face masks, frequent hand washing
and social distancing measures, including school closings and public
circulation limitations (15). In this study, in 2020, the number of
cases of ALRIs decreased after the establishment of a national-wide
lockdown at the end of the summer (16), remaining very low during the
rest of the year, without showing a characteristic winter peak. This
phenomenon is similar to that reported in other countries in the
Southern Hemisphere, such as Brazil (17) and Australia (18), where there
was a decrease in cases of bronchiolitis and hospitalizations for
respiratory causes among the pediatric population in that period. In the
Northern Hemisphere, during the first pandemic winter (2020-2021) and
with mitigation measures still in force, similar findings were
described: in cities in northern Italy (19) and in England (20), a
decrease was observed in the number of pediatric hospitalizations and,
particularly, in the incidence of RSV bronchiolitis between October 2020
and March 2021.
During 2021, mitigation measures gradually decreased, and the
circulation of common respiratory viruses reappeared (21). In this
study, the cases of ALRIs increased in winter 2021 but later and with a
somewhat lower intensity than in the prepandemic years (2018-2019). This
phenomenon was also reported in relation to cases of RSV infection in
pediatric hospitals in Buenos Aires (22,23). A similar delay in the
onset of respiratory infections was observed in the Northern Hemisphere
in the winter of 2021-2022 (24,25).
In 2022, the winter increase in ALRIs cases occurred earlier and with
greater intensity than in 2021, approaching prepandemic values.
Something similar was observed in the Northern Hemisphere (2022-2023),
with the seasonal cycle of RSV circulation moving toward prepandemic
patterns (25).
As mentioned above, most of the studies on the impact of the pandemic on
pediatric respiratory infections include hospitalized patients and/or
those affected by RSV or influenza. As the spectrum of viruses
responsible for ALRIs in outpatients may be different (including
rhinoviruses and parainfluenza viruses) (26), the impact could have been
different in these patients. However, our study, which included only
outpatient visits, showed similar results, indicating that the impact of
the pandemic was similar for all viruses responsible for ALRIs.
During the pandemic, the circulation of respiratory viruses was greatly
altered, and there were questions regarding whether the usual pattern
would re-emerge (27). This study provides evidence that a return to the
usual seasonal patterns of viral circulation is occurring.
The pandemic highlighted, on several occasions, the need to be prudent
in forecasting. In particular, children were affected by the pandemic in
an indirect way (not related to the SARS-Cov2 virus) but to a much
greater extent (domestic violence, eating disorders, anxiety, etc.)
(28).
Although there is a return of the circulation of common respiratory
viruses to prepandemic patterns, it is unknown whether the immunological
debt (29) of children has been fully settled or if a different pattern
will emerge next winter.
Conclusion
Outpatient visits for ALRIs decreased significantly in the city of
Buenos Aires during the COVID-19 pandemic and currently seem to have
recovered their magnitude and seasonality.