This paper investigates the influence of air temperature and relative humidity on the transmission of COVID-19 . After estimating the serial interval of COVID-19 from 105 hand-collected pairs of the virus carrier and the infected, we calculate the daily effective reproductive number, R, for each of all 100 Chinese cities with more than 40 cases . Using the daily R values from January 21 to 23,2020 as proxies of non-intervened transmission intensity, we find, under a linear regression framework, high temperature and high humidity significantly reduce the transmission of COVID-19 , respectively.One-degree Celsius increase in temperature and one percent increase in relative humidity lower R by 0.0225 and 0.0158,respectively. This result is consistent with the fact that the high temperature and high humidity reduce the transmission of influenza and SARS. It indicates that the arrival of summer and rainy season ] ] ] ] in the northern hemisphere can effectively reduce the transmission of the COVID-19. We also developed a website to provide R of major cities around the world according to their daily temperature and relative humidity: URL
With the ongoing global pandemic of COVID-19, a question is whether the coming summer in the northern hemisphere will reduce the transmission intensity of COVID-19 with increased humidity and temperature. In this paper, we investigate this problem using the data from the cases with symptom-onset dates from January 19 to February 10, 2020 for 100 Chinese cities , and cases with confirmed dates from March 15 to April 25 for 1,005 U.S. counties. Statistical analysis is performed to assess the relationship between the transmissibility of COVID-19 and the temperature/humidity, by controlling for various demographic, socio-economic, geographic, healthcare and policy factors and correcting for cross-sectional correlation. We find a similar influence of the temperature and relative humidity on effective reproductive number (R values) of COVID-19 for both China and the U.S. before lockdown in both countries: one-degree Celsius increase in temperature reduces R value by about 0.023 (0.026 (95\% CI -0.0395,-0.0125]) in China and 0.020 (95\% CI -0.0311, -0.0096]) in the U.S.), and one percent relative humidity rise reduces R value by 0.0078 (0.0076 (95\% CI -0.0108,-0.0045]) in China and 0.0080 (95\% CI -0.0150,-0.0010]) in the U.S.). If assuming a 30 degree and 25 percent increase in temperature and relative humidity from winter to summer in the northern hemisphere , we expect the R values to decline about 0.89 (0.69 by temperature and 0.20 by humidity). Given the notion that the non-intervened R values are around 2.5 to 3, only weather factors cannot make the R values below their critical condition of R<1, under which the epidemic diminishes gradually. Therefore, public health intervention such as social distancing is crucial to block the transmission of COVID-19 even in summer.
R
This paper investigates the influence of air temperature and relative humidity on the transmission
With the ongoing global pandemic of COVID-19, a question is whether the coming summer in the northern hemisphere will reduce the transmission intensity
R
. After estimating the serial interval of COVID-19 from 105 hand-collected pairs of the virus carrier and the infected, we calculate the daily effective reproductive number, R, for each of all
with increased humidity and temperature. In this paper, we investigate this problem using the data from the cases with symptom-onset dates from January 19 to February 10, 2020 for
R
with more than 40 cases . Using the daily R values from January 21 to 23,2020 as proxies of non-intervened transmission intensity, we find, under a linear regression framework, high temperature and high humidity significantly reduce the transmission
, and cases with confirmed dates from March 15 to April 25 for 1,005 U.S. counties. Statistical analysis is performed to assess the relationship between the transmissibility of COVID-19 and the temperature/humidity, by controlling for various demographic, socio-economic, geographic, healthcare and policy factors and correcting for cross-sectional correlation. We find a similar influence of the temperature and relative humidity on effective reproductive number (R values)
R
, respectively.One-degree
for both China and the U.S. before lockdown in both countries: one-degree
R
and one percent increase in relative humidity lower R by 0.0225 and 0.0158,respectively. This result is consistent with the fact that the high temperature and high humidity reduce the transmission of influenza and SARS. It indicates that the arrival of summer and rainy season
reduces R value by about 0.023 (0.026 (95\% CI
A
-0.0395,-0.0125
A
) in China and 0.020 (95\% CI
A
-0.0311, -0.0096
A
) in the U.S.), and one percent relative humidity rise reduces R value by 0.0078 (0.0076 (95\% CI
A
-0.0108,-0.0045
A
) in China and 0.0080 (95\% CI
A
-0.0150,-0.0010
A
) in the U.S.). If assuming a 30 degree and 25 percent increase in temperature and relative humidity from winter to summer
R
can effectively reduce the transmission of the COVID-19. We also developed a website to provide R of major cities around the world according to their daily temperature and relative humidity: URL
, we expect the R values to decline about 0.89 (0.69 by temperature and 0.20 by humidity). Given the notion that the non-intervened R values are around 2.5 to 3, only weather factors cannot make the R values below their critical condition of R<1, under which the epidemic diminishes gradually. Therefore, public health intervention such as social distancing is crucial to block the transmission of COVID-19 even in summer.