1
Implications of Monsoon Season
& UVB Radiation
for COVID-19 in India
Manuscript
Rahul Kalippurayil Moozhipurath*
1
, Lennart Kraft
1
(Faculty of Economics and Business, Goethe University Frankfurt
1
)
Rahul Kalippurayil Moozhipurath; Lennart Kraft; Faculty of Economics and Business, Goethe
University Frankfurt, Theodor-W.-Adorno-Platz 4, 60629 Frankfurt, Germany; email:
rahulkm85@gmail.com, Phone: +49-152-1301-0589; email: lennart.kraft@wiwi.uni-frankfurt.de;
Phone +49-69-798-34769;
All rights reserved. No reuse allowed without permission.
perpetuity.
preprint (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in
The copyright holder for thisthis version posted September 25, 2020. ; https://doi.org/10.1101/2020.09.24.20200576doi: medRxiv preprint
NOTE: This preprint reports new research that has not been certified by peer review and should not be used to guide clinical practice.
2
Abstract
Background. India has recorded 66,333 deaths over 36 administrative regions placing India
third in the world after the US and Brazil for COVID-19 deaths as of 2 September 2020.
Studies indicate that south-west monsoon season plays a role in the dynamics of contagious
diseases, which tend to peak post-monsoon season. Recent studies show that vitamin D and its
primary source Ultraviolet-B radiation (UVB) may play a protective role in mitigating
COVID-19 deaths. However, the combined roles of the monsoon season and UVB in
COVID-19 in India are still unclear. In this observational study, we empirically study the
respective roles of monsoon season and UVB, whilst further exploring, whether monsoon
season negatively impacts the protective role of UVB in COVID-19 deaths in India.
Methods. We use a log-linear Mundlak model to a panel dataset of 36 administrative regions
in India from 14 March 2020 - 8 August 2020 (n=4005). We use the cumulative COVID-19
deaths as the dependent variable. We isolate the association of monsoon season and UVB as
measured by Ultraviolet Index (UVI) from other confounding time-constant and time-varying
region-specific factors.
Findings. After controlling for various confounding factors, we observe that the monsoon
season and a unit increase in UVI are separately associated with 12.8 percentage points and
2.0 percentage points decline in growth rates of COVID-19 deaths in the long run. These
associations translate into substantial relative changes. For example, the current monsoon
season, that has been going on for two weeks, is associated with a reduction in growth rates of
COVID-19 deaths of 59%, whereas a permanent unit increase of UVI is associated with a
reduction in growth rates of COVID-19 deaths of 37%. However, the current monsoon
season, also reduces the protective role of UVI by 16.3% [0.33 percentage points], plausibly
due to lower UVB exposure.
All rights reserved. No reuse allowed without permission.
perpetuity.
preprint (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in
The copyright holder for thisthis version posted September 25, 2020. ; https://doi.org/10.1101/2020.09.24.20200576doi: medRxiv preprint
3
Interpretation. We find independent protective roles of both the monsoon season and UVI in
mitigating COVID-19 deaths. Furthermore, we find evidence that monsoon season is
associated with a significant reduction in the protective role of UVI. The protective role of
monsoon season is plausibly due to limited outdoor activities of people. Our study outlines
the role of the monsoon season and UVB in COVID-19 in India and supports health-related
policy decision making in India.
All rights reserved. No reuse allowed without permission.
perpetuity.
preprint (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in
The copyright holder for thisthis version posted September 25, 2020. ; https://doi.org/10.1101/2020.09.24.20200576doi: medRxiv preprint
4
1 Introduction
COVID-19 has caused unparalleled economic and health disruptions in India, the second
most populated country with over 1.3 billion people. As of September 2, India has reported
66,333 COVID-19 deaths across 36 administrative regions, placing India third in the world
behind the US and Brazil
1
.
Recent observational and clinical studies show that vitamin D deficiency might be linked
to incidence
2,3
, severity
4
5
and mortality
6–8
associated with COVID-19. Recent studies show
that vitamin D and its primary source Ultraviolet-B radiation (UVB) may play a protective
role in mitigating COVID-19 deaths
9,10
. Studies indicate that south-west monsoon season
(monsoon season) plays a role in the dynamics of contagious diseases, which tend to peak
post-monsoon season
11
. The respective roles of the monsoon season and UVB in COVID-19
in India are still unclear. We anticipate a sudden increase in contagious diseases during and
post monsoon season, which will stress India’s healthcare system
12,13
. Limited hours of
sunlight and dense cloud cover
14
limit the intensity of UVB radiation, mitigating its protective
role
9
during the monsoon season. Even though limited outdoor activities during the monsoon
season may decrease the likelihood of transmission; we anticipate that it may also lead to a
lower likelihood of UVB exposure, further mitigating its protective role. To the best of our
knowledge, so far, no empirical study has explored the roles of the monsoon season and UVB
in COVID-19 in India, specifically studying the association between monsoon season, the
subsequent reduced exposure likelihood of UVB radiation and COVID-19 deaths in India.
In this observational study, we empirically describe the roles of the monsoon season and
further explore, whether monsoon season result in a reduction in the protective role of UVB in
COVID-19 deaths in India. After controlling for various confounding factors, we observe that
in the long run the monsoon season and a unit increase in UVI are separately associated with
12.8 percentage points [p<0.05] and 2.0 percentage points [p<0.05] decline in COVID-19
All rights reserved. No reuse allowed without permission.
perpetuity.
preprint (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in
The copyright holder for thisthis version posted September 25, 2020. ; https://doi.org/10.1101/2020.09.24.20200576doi: medRxiv preprint
5
deaths growth rate. On the other hand, in the long run the monsoon season reduces the
protective role of UVI by 1.3 percentage points [p<0.05], plausibly due to lower UVB
exposure. Consequently, it is expected that although the monsoon season is helping mitigate
the transmission of Covid-19, it is doing so at the cost of UVB exposure.
2 Impact of Monsoon on Healthcare System, UVB
Radiation & COVID-19 Deaths in India
Studies indicate that the monsoon season and post-monsoon season may be associated
with the peaks of contagious diseases like influenza, i.e., July-September
11,15,16
. Heavy rainfall
linked to monsoon season may create situations favourable for the outbreaks of infectious
diseases such as diarrheal disease, cholera, dengue, typhoid as well as respiratory diseases
17
.
Furthermore, the temporal overlap between these contagious diseases and COVID-19 may
give rise to significant health care challenges
12
. The consequences of possible coinfection
with these infectious diseases and SARS-CoV-2 are largely unknown
12,13
. Moreover, we
anticipate this sudden increase in contagious diseases during monsoon season to create stress
in the healthcare system, further restricting the hospital capacity required for COVID-19
patients
12,13
. Heavy precipitation may also cause disruptions in traffic, limiting the
transportation possibilities of COVID-19 patients
13
. On the other hand, the monsoon season
also plays a protective role due to restricted mobility
18
as people are more likely to stay
indoors, reducing the possibility of the transmission of the virus. In general, the impact of the
monsoon season on COVID-19 in India remains largely unknown.
In addition to the above consequences in the healthcare system, another important
consequence of the monsoon season is the higher precipitation and the reduced likelihood of
UVB exposure and subsequently lower vitamin D levels
19
. Studies indicate that UV radiation
inactivates viruses in fomite transmission
20
. UVB also plays another protective role via its
role in vitamin D skin synthesis
21–25
, as dietary intake (natural food, fortified food or
All rights reserved. No reuse allowed without permission.
perpetuity.
preprint (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in
The copyright holder for thisthis version posted September 25, 2020. ; https://doi.org/10.1101/2020.09.24.20200576doi: medRxiv preprint
