Asymptomatic Cases, the Hidden Challenge in Predicting COVID-19 Caseload Increases

Abstract

The numbers of novel coronavirus cases continue to grow at an unprecedented rate across the world. Attempts to control the growth of the virus using masks and social-distancing, and, recently, double-masking as well, continue to be difficult to maintain, in part due to the extent of asymptomatic cases. Analyses of large datasets consisting of 219,075 individual cases in Ontario, indicated that asymptomatic and pre-symptomatic cases are substantial in number. Large numbers of cases in children aged 0–9 were asymptomatic or had only one symptom (35.0% and 31.4% of total cases, respectively) and resulted in fever as the most common symptom (30.6% of total cases). COVID-19 cases in children were more likely to be milder symptomatic with cough not seen as frequently as in adults aged over 40, and past research has shown children to be index cases in familial clusters. These findings highlight the importance of targeting asymptomatic and mild infections in the continuing effort to control the spread of COVID-19. The Pearson correlation coefficient between test positivity rates and asymptomatic rates of −0.729 indicates that estimates of the asymptomatic rates should be obtained when the test positivity rates are lowest as the best approach.

The SIR model towards the Data One year of Covid-19 pandemic in Italy case study and plausible "real" numbers.

“…Generation time, infectious period and effective reproduction number have been sought from the data through the model. At the very end, the curve of the swab-confirmed infectious individuals has been completed for the proportion of infection transmissions likely occurred from individuals with no symptoms, using figures published in important works ( [22][23][24][25] ). Thus an estimate of the "real numbers" of the pandemic in Italy is obtained for the considered period of time.…”

“…Crucial is the fact that the model is scale-invariant, thus allowing to conveniently choose as a reference one sub-compartmental curve whose real data can be considered reliable, such as the swab-confirmed infectious individuals curve. This choice is done indeed here: swab-confirmed infectious are mostly individuals who have developed symptoms and are actually found to cover a nearly constant fraction of all the infectious people, given the circumstances that symptomatic and a-symptomatic individuals roughly are respectively fractions of the age groups of over sixty and younger people ( [23,[27][28][29]). The case of the second through the third pandemic wave of Covid-19 in Italy is studied.…”

“…There are several studies on the relevance of SARS-CoV-2 transmission from asymptomatic people, like [22][23][24][25] and references therein. Quite recent and complete is ref.…”

The SIR model towards the data

“…Crucial is the fact that the model is scale-invariant, thus allowing to conveniently choose as a reference one sub-compartmental curve whose real data can be considered reliable, such as the swab-confirmed infectious individuals curve. This choice is done indeed here: swab-confirmed infectious are mostly individuals who have developed symptoms and are actually found to cover a nearly constant fraction of all the infectious people, given the circumstances that symptomatic and asymptomatic individuals roughly are, respectively, fractions of the age groups of over sixty and younger people ( [8][9][10][11]). The case of the second through the third pandemic wave of Covid-19 in Italy is studied.…”

“…There are several studies on the relevance of SARS-CoV-2 transmission from asymptomatic people, like [8,[23][24][25] and references therein. Quite recent and complete is ref.…”