Coronavirus outbreak, Coronavirus disease (COVID-19), Impact of higher temperatures on coronavirus
Coronavirus disease (COVID-19), which began in Wuhan in December 2019, has become a global concern. WHO has declared it a pandemic. COVID-19, an illness caused by novel coronavirus, has caused over 6000 deaths across the globe (Worldometer, 2020). The threatening consequences of novel coronavirus have pushed researchers and epidemiologists to learn more about involved pathogens on an urgent basis.
Some
meteorologists and medical specialists are searching for a seasonal approach to
coronavirus. Keeping in view the similarities of COVID-19 disease with flu,
scientists are expecting this disease to have a distinct winter peak in the
cold areas because viruses associated with cold and flu are also more likely to
spread during winter. The intensity of the disease is expected to decrease
during the spring and summer season. But, the presence of the viruses may not
completely be eliminated during summer (Harvard
Medical School, 2020).
Scientists
are interested in understanding the dependency of 2019-nCoV (novel coronavirus)
virus on temperature because the 2019-nCoV virus belongs to the family of SARS
coronavirus (SARS-CoV). SARS-CoV was transmitted
from cats to humans in China in 2002. Researchers have already
investigated the SARS-CoV virus and found that this virus is less likely to
spread at higher temperatures. The current 2019-nCoV
is believed to be caused by snakes or rabbits and can cause respiratory disease
on the same pattern as SARS-CoV does. These respiratory diseases can be
transmitted from one person to another person (CDC, 2020).
The experimental study conducted by Chan et al. concluded
that higher temperatures at higher relative humidity can have a synergistic
impact on the inactivation of SARS-CoV capabilities. Whereas, lower
temperatures and lower humidity cause the prolonged existence of viruses on a
contaminated surface. The environmental conditions having higher temperatures
and higher humidity levels are therefore not likely to support the spread of
the virus. Moreover, the excess use of air-conditioning can reduce the humidity
and in turn promotes the spread of the virus. The researchers have also found
that the threat of enhanced chance of SARS-CoV was 18.8-folds greater in days
having lower air temperature than the days having higher temperatures in
Hong-Kong (Chan et al., 2011).
Another
study conducted by Casanova et al. assessed the risk posed by SARS coronavirus (SARS-CoV)
on environmental surfaces under different environmental variables. This study
also reported similar results as found by Chan et al. The researchers found
that survival of the virus increased at lower air temperatures. A similar
relation was found between air temperatures and inactivation for viruses
enveloped in aerosols and liquids. Overall, lower humidity improves the chances
of virus survival. But, the study found that relative humidity plays a lesser
role at temperatures of 40oC and above. At 40oC, all
three humidity levels (20%, 50%, 80%) caused rapid inactivation of SARS
coronavirus. The study has also suggested that the relationship between air
temperature, relative humidity, and virus inactivation can vary depending on
types of viruses (Casanova et al., 2010).
Another group of experts has explained the relation between
virus spread and hot weather in a different way. They argued that during the
summer season people are less likely to gather outside in hot weather.
Increased air circulation within buildings and enhanced UV light from the
sunshine can help reduce the transmission of viruses in hotter weather.
Moreover, the pattern of spread of virus so far also suggests
that the outbreak has mostly hit the areas with colder climates. The head of
RTIICS (“RN Tagore International Institute of Cardiac Sciences”) Souren Panja,
in an interview with Times of India, briefed that weather can definitely be a
deterrent for the attack of coronavirus in hotter areas.
RTIICS head further explained that the spread of nCoV is critical
in countries with colder temperatures. For example, maximum cases have been
reported in Wuhan where sub-zero minimum temperature was reported during
January and February. Another case is Seoul in South Korea where a sharp
increase in cases of coronavirus was found. The temperature found there was
also mostly below or close to 0oC in February. Similarly, the temperatures in countries like Italy, the US, and Iran etc. were below 10oC in February and during the early days of March that supported the virus
activation.
On the other hand, coronavirus entered India and Pakistan when the winter was almost over. At present, the
moderate temperatures in India and Pakistan, combined with the precautionary
measures taken by respective governments have somehow restricted the outbreak
at large scale. So, if we take into consideration the patterns of coronavirus
spread, findings of existing research works, hypotheses of scientists, and the
family terms between 2019-nCoV and SARS-CoV, it can be believed that spread of
coronavirus at large scale is less likely to take place if the temperature
rises above 35oC. The situation is believed to become better as the
temperature rises further. Experts have also recommended to avoid
air-conditioning and visiting low humidity surroundings and low-temperature
areas in order to lower the chances of getting exposed to coronavirus.
Sources
Casanova,
L. M., Jeon, S., Rutala, W. A., Weber, D. J., & Sobsey, M. D. (2010).
Effects of air temperature and relative humidity on coronavirus survival on
surfaces. Appl. Environ. Microbiol., 76(9), 2712-2717.
CDC. (2020). Coronavirus Disease 2019 (COVID-19). Retrieved
15 March 2020, from https://www.cdc.gov/coronavirus/2019-ncov/about/index.html
Chan, K. H., Peiris, J. S., Lam, S. Y., Poon, L. L. M., Yuen,
K. Y., & Seto, W. H. (2011). The effects of temperature and relative
humidity on the viability of the SARS coronavirus. Advances in virology, 2011.
Harvard Medical School. (2020). Coronavirus Resource Center -
As coronavirus spreads, many questions and some answers. Retrieved 15 March
2020, from https://www.health.harvard.edu/diseases-and-conditions/coronavirus-resource-center
Worldometer. (2020). COVID-19 CORONAVIRUS OUTBREAK. Retrieved
15 March 2020, from https://www.worldometers.info/coronavirus/
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