Children with mild COVID-19 have much higher levels of genetic material for the virus in the nose compared to older children and adults


A study from Ann & Robert H. Lurie Children’s Hospital of Chicago discovered that children younger than 5 years with mild to moderate COVID-19 have much higher levels of genetic material for the virus in the nose compared to older children and adults.

Findings, published in JAMA Pediatrics, point to the possibility that the youngest children transmit the virus as much as other age groups.

The ability of younger children to spread COVID-19 may have been under-recognized given the rapid and sustained closure of schools and daycare during the pandemic.

“We found that children under 5 with COVID-19 have a higher viral load than older children and adults, which may suggest greater transmission, as we see with respiratory syncytial virus, also known as RSV,” says lead author Taylor Heald-Sargent, MD, PhD, pediatric infectious diseases specialist at Lurie Children’s and Assistant Professor of Pediatrics at Northwestern University Feinberg School of Medicine.

“This has important public health implications, especially during discussions on the safety of reopening schools and daycare.”

Dr. Heald-Sargent and colleagues analyzed 145 cases of mild to moderate COVID-19 illness within the first week of symptom onset. They compared the viral load in three age groups – children younger than 5 years, children 5-17 years and adults 18-65 years.

“Our study was not designed to prove that younger children spread COVID-19 as much as adults, but it is a possibility,” says Dr. Heald-Sargent. “We need to take that into account in efforts to reduce transmission as we continue to learn more about this virus.”

OVID-19 has heavily affected nursing homes for elderly people in Italy and particularly in the Lombardy region, causing uncountable deaths.

From the moment the pandemic slowly faded, there has been a pressing scientific and social need to define a limit of time and of viral load beyond which the positivity of RT-PCR loses its meaning, to reduce the isolation of the subjects in the nursing homes beyond the clinical and public health utility.

While the decline in viral infectivity seems to decline in one or two weeks since symptom onset1, 2 the RT-PCR positivity may persist for several weeks after the resolution of symptoms3, 4, 5, 6.

Since there is a minimal risk for persistently-positive recovered patients to shed infectious virus, many of them remain hospitalized, or in shelter-in-place, for a much longer time than necessary, with significant social distress and economic commitment.

Few data are available so far in children and adolescent nursing homes regarding quantitative RT-PCR (qRT-PCR) registered during the COVID-19 pandemic.

Fifty-two children and adolescents (41 males 11 females: mean age 14.8, range 6–18 years) affected by neuropsychiatric disorders and resident in Villa Santa Maria Rehabilitation Institute, a well-known nursing home in Lombardy region, underwent a series of qRT-PCR on nose-pharyngeal swabs from April 27 to July 4th, 2020.

Thirty-two subjects had symptoms suggestive of COVID-19 infection, like fever, cough, and or diarrhea while 20 were asymptomatic. Sixty-two percent of symptomatic subjects and 50% of asymptomatic subjects resulted positive to COVID-19 with a total of 30 positive cases (25 males – 5 females; mean age 14.1 years).

Subjects showing positivity to the test were monitored throughout with repeated tests on a 1–2-week basis until the obtainment of two consecutive negative tests. We had to wait till July 4th to certify the negative turning of all subjects.

Interesting details of viral load in the 30 subjects positive at RT-PCR were observed according to different subgroup characteristics.

The initial viral load of 25 males was significantly higher than 5 females (median [IQR] males: 19 [14 – 23,5] vs. 27 [24–29], respectively; p = 0.01 by Mann-Whitney test).

Initial viral load observed in 21 symptomatic subjects resulted substantially higher in comparison with 9 asymptomatic subjects (median [IQR] with symptoms: 20 [15 –27] vs. 22 [16.5–25], respectively; the difference anyway resulted statistically not significant (p = 0.8 Mann–Whitney test).

The viral load at the first swab in 16 subjects who remained still positive at second swab was higher in comparison with 14 subjects who resulted negative at second swab. Also in this case the difference resulted statistically not significant (median CT[IQR] still positive: 19.5 [14.5 –23.7] vs. 22 [17.7–27], respectively (p = 0.4 Mann–Whitney test).

Twenty subjects underwent more than two RT-PCR tests until permanent negative turning.

Fig. 1 shows the oscillation of viral load in the subsequent 97 swabs, performed along 12 weeks after the first swab. A marked oscillation of viral load value was observed, also with negative swabs turning positive.

Fig. 1
Fig. 1
Cycle-thresholds (CT) values oscillation in 20 subjects undergoing repeated COVID-19 RT-PCR tests (values above 40 are considered negative).

This study shows that in children and adolescents found positive at COVID-19 RT-PCR being resident in a nursing home the time required for a definitive disappearance of the virus from nose-pharyngeal swab can overcome two months. Along this period is possible to observe the existence of discrete oscillation in COVID-19 viral load count in line with the results of a recent Italian study7. Given these findings, the WHO resolution for releasing COVID-19 patients from isolation seems reasonable to avoid unnecessary social burden8.


1. Wolfel R., Corman V.M., Guggemos W., Seilmaier M., Zange S., Muller M.A. Virological assessment of hospitalized patients with COVID-2019. Nature. 2020;581(7809):465–469. , PubMed PMID: 32235945. [Abstract] [Google Scholar]

2. Bullard J., Dust K., Funk D., Strong J.E., Alexander D., Garnett L. Predicting infectious SARS-CoV-2 from diagnostic samples. Clin Infect Dis. 2020:ciaa638,. PubMed PMID: 32442256. [Europe PMC free article] [Abstract] [Google Scholar]

3. Peng J., Wang M., Zhang G., Lu E. Seven discharged patients turning positive again for SARS-CoV-2 on quantitative RT-PCR. Am J Infect Control. 2020;48(6):725–726. , PubMed PMID: 32317126. Pubmed Central PMCID: 7151314. [Europe PMC free article] [Abstract] [Google Scholar]

4. Fu W., Chen Q., Wang T. Letter to the Editor: three cases of re-detectable positive SARS-CoV-2 RNA in recovered COVID-19 patients with antibodies. J Med Virol. 2020 doi: 10.1002/jmv.25968. , PubMed PMID: 32369214. [CrossRef] [Google Scholar]

5. Woodruff A. COVID-19 Follow up Testing. J Infect. 2020, PubMed PMID: 32407758. Pubmed Central PMCID: 7212964.

6. Liu W.D., Chang S.Y., Wang J.T., Tsai M.J., Hung C.C., Hsu C.L. Prolonged virus shedding even after seroconversion in a patient with COVID-19. J Infect. 2020 , PubMed PMID: 32283147. Pubmed Central PMCID: 7151379. [Google Scholar]

7. Cento V., Colagrossi L., Nava A., Lamberti A., Senatore S., Travi G. Persistent positivity and fluctuations of SARS-CoV-2 RNA in clinically-recovered COVID-19 patients. J Infect. 2020 doi: 10.1016/j.jinf.2020.06.024. , S0163-4453(20)30405-9. Epub ahead of print. PMID: 32574567. [CrossRef] [Google Scholar]

8. World Health Organization. Criteria for releasing COVID-19 patients from isolation. Scientific brief 2020.

Ann & Robert H. Lurie Children’s Hospital of Chicago



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