As recently reported in this journal, measures implemented to contain COVID-19 infection also seems to be effective in reducing influenza activity in Singapore (1) . The same effect was also reported to reduce the spread of viral respiratory diseases, particularly influenza viruses, in countries such as Taiwan, Japan (2, 3) , Australia, and New Zealand (https://info.flutracking.net).
São Paulo is the largest city in Brazil and aggregates the majority of COVID-19 cases registered in the country so far. Since the first detection of SARS-CoV-2 in Brazil, on February 25, the country accounts (on May 9) 148,670 confirmed cases and 10,100 deaths of which 41,830 and 3,416 were registered in São Paulo, respectively.
According to the weekly epidemiological records for influenza viruses in the city of São Paulo, comprising the corresponding period of our study (11 th to 16 th epidemiological weeks), in the last four years, influenza A and B viruses were circulating and sometimes at the peak of the season (Fig.   1 ). Virus screening was carried out with AgPath-ID One-Step RT-PCR Reagents on 20 µL of total reaction volume. SARS-CoV-2 detection was performed with oligonucleotides described by the Centers for Disease Control and Prevention (CDC) (5) . The detection of IV-A, IV-B, hMPV, and RSV was performed with oligonucleotides described elsewhere (6) (7) (8) .
Overall, 115 patients were positive for SARS-CoV-2, four for IV-B, nine children for RSV, and none for IV-A and hMPV (Table 1) . A 36-year-old patient was co-infected with SARS-CoV-2 and IV-B, who had a favorable outcome and was discharged after six days. We observed the absence of IV-A and only 1.64% of IV-B and 0.41% of hMPV, which demonstrates a reduction of expected cases of infection by influenza virus in relation to the registered cases in the city during the same period, in the last 4 years (Fig. 1) . interestingly, during the pandemic influenza A (H1N1) pdm09 in 2009, hMPV was the second most prevalent virus in adults in a study carried out by our research group (9) . For RSV, 25% of investigated children were positive. However, the RSV infection rate in hospitalized children is usually higher than 50% at this time of year (10) . The results suggest that the containment measures adopted in the city for COVID-19 restraint contributed to reducing the spread of influenza viruses and RSV among children.
One limitation of the present study was not to retrieve the vaccination status of the elderly, although the vaccination and study time frame overlapped and it is expected that the production of antibodies will take at least 15 days after vaccination.
None.