WHO defines an asymptomatic case as a laboratory-confirmed infected person without overt symptoms.1It remains to be established how thoroughly such a person needs to be examined clinically. Furthermore, there is a distinction between asymptomatic and presymptomatic individuals which can currently be made onlyretrospectively, after the occurrence or non-occurrence of clinical symptoms.
Recent evidence suggests that elevated serum/plasma lactate dehydrogenase levels may, already in the early stages, be indicative of presymptomatic infections and, thus, facilitate early differentiation.2 However, it is these asymptomatic individuals carrying SARS-CoV-2 that are hidden drivers of the pandemic, and infectivity studies confirm the existence of transmission by asymptomatic individuals.Younger age correlates strongly with asymptomatic and mild infections and children as hidden drivers. The estimated proportion of asymptomatic infections ranges from 18% to 81%,3 however, the transmission risk from these asymptomatic individuals remains low as per reports and analysis published in the world’s no. 1 journal Nature, because scientists they are not coughing or sneezing as much. 4
Nevertheless, there are many accounts of SARS‐CoV‐2 spreading by proximity with asymptomatic individuals who do not know they are infected; these could be the individuals that may notbe coughing or sneezing. On almost a daily basis, scientists from the CDC and the National Institutes of Health (NIH) discuss the importance of curbing transmission from asymptomatic individuals, few of which we have covered in this report.5
Early on, when the main geographical regions with cases of COVID‐19 were in China, there were reports in the press regarding asymptomatic transmission suggesting that coughing and sneezing might not be the only important means of spreading active virus, leading to hypothesized pathways such as touching of surfaces and shedding of particles in the process of normal breathing.
Researchers in China had indicated early on that asymptomatic transmission was a possibility after studying five family members who became symptomatic after contact with an asymptomatic family member who was visiting from Wuhan.6Similarly, other researchers identified viral loads in an asymptomatic subject, with unremarkable CT scans, that were similar to the symptomatic subjects.7Wei et al. investigated all 243 cases of COVID‐19 reported in Singapore between January 23 and March 168and were able to identify presymptomatic transmission as the most likely explanation in seven clusters of cases in the analysis.
Therefore, it is definitely a good idea to follow precautions irrespective of the individual or group around you being symptomatic or not. Universal use of masks can prevent inadvertent spread by an asymptomatic person who is not aware of his/her positive status. It is also important to maintain a distance of at least six feet from any individual, apart from handwashing or use of sanitizers, and maintenance of personal hygiene. At home, it is best to wear a mask, especially if there are elderly people in the house. but if that is not possible, it is advisable to cover one’s mouth when coughing or sneezing or to do so into one’s elbow. In public transports or in closed settings, such as office spaces, it is recommended to wear masks – even if they are just multi-layered fabric masks, to prevent the spread of active transmission to the maximum.
Source:
1 WHO defines an asymptomatic case as a laboratory-confirmed infected person without overt symptoms
2 Ooi EE, et al. Asymptomatic SARS-CoV-2 infection. Lancet Infect Dis. 2020 doi: 10.1016/S1473-3099(20)30460-6.
3 Nikolai LA, et al. Asymptomatic SARS Coronavirus 2 infection: Invisible yet invincible. Int J Infect Dis. 2020;100:112–16. doi: 10.1016/j.ijid.2020.08.076
4 Nogardy B. What the data say about asymptomatic COVID infections. Nature 2020;587:534.
5 Anderson EL, et al. Consideration of the Aerosol Transmission for COVID‐19 and Public Health. Risk Anal. 2020;40(5):902–07. doi: 10.1111/risa.13500
6 Bai Y, et al. Presumed asymptomatic carrier transmission of COVID‐19. JAMA 2020:323(14):1406–07.
7 Zou L, et al. SARS‐CoV‐2 viral load in upper respiratory specimens of infected patients. New Engl J Med 2020;382(12):1177–79.
8 Wei WE, et al.Presymptomatic transmission of SARS‐CoV‐2—Singapore, January 23–March 16, 2020. Morbidity and Mortality Weekly Report, 69(14), 411.
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