COVID-19 Update: How climate change can trigger disease emergence

The author discusses issues of climate change and pandemics, the controversy about the number of COVID deaths, COVID sub-variants, new SARS-CoV-2 vaccines, post-covid complications, long COVID symptoms and possible treatments.

ByDebananda S Ningthoujam

Updated 8 May 2022, 8:02 am

(File Photo: IFP)
(File Photo: IFP)

A new study reports that climate change could trigger the next deadly pandemic. This study was conducted by scientists working at Georgetown University Medical Center, Washington, DC, USA.

They proposed that the rising temperature will cause relocation of wild animals to areas with large human populations. This forced mingling of human and animal populations will drastically increase the risks of viral spillovers that would lead to outbreaks of zoonotic viral pandemics in the near future (TOI, May 6, 2022).

This work has recently been published in the April 28 issue of the prestigious journal Nature. The population shifts caused by climate change will lead to emergence of dangerous viruses such as Ebola and coronaviruses in new areas and into new types of animals, facilitating the viral jump from "stepping stone" intermediate hosts into humans.

SARS-COV-2 is believed to have jumped from wildlife into humans when they were brought together in wildlife markets in China. But such wildlife trade may not be the major cause of zoonotic diseases anymore. The main trigger can now be climate change. Already the earth is warmer by about 1.2 degrees Celcius and global climatic change can only worsen unless there is global political consensus to conserve forests and drastically cut down greenhouse gas emissions.

The rising temperature will also profoundly impact bats; they are considered to be major reservoirs of unknown viruses, and, as they can fly, they can fly long distances to share their viruses with new mammalian populations. The worst impact may be felt in southeast Asia, a global hotspot of bat diversity. Thus, climate change could become the biggest risk for disease emergence, more than wildlife trade, industrial agriculture and deforestation. Global efforts are now needed to track wildlife disease surveillance in areas with greatest environmental change.

Controversy surrounding number of COVID Deaths

WHO's latest report says that nearly 4.7 million people are thought to have died in India due to COVID-19 and 10 times higher than the official records (BBC News, May 6, 2022).

The Government of India, however, has rejected the WHO data, claiming that the latter's methodology is inappropriate. The WHO data in based on the number of excess deaths, a measure of how many more people are dying than expected compared to previous years. India has officially logged a little more than 5 lakh deaths during Jan 1, 2020-December 31, 2021. WHO puts the figure at nearly 10 times higher. If what WHO says is correct, India accounts for almost a third of COVID deaths globally.

The BBC report says that India's real COVID death toll may never be known.

New COVID Sub Variants

Two new subtypes of Omicron have been detected in the UK (Times Now, May 6, 2022). The new sub variants are called BA.4 and BA.5, which are also spreading very fast in South Africa. BA.2 was the first sub variant of Omicron to overtake its predecessor. Now, t seems BA.4 and BA.5 or other subtypes may supersede BA.2 or other subtypes of Omicron.

Prof Tim Spector, King's College London, says that two symptoms of COVID must be taken very seriously. These are - loss of smell and tinnitus (ringing in the ear).


As per the ZOE COVID study, about 20 per cent Covid-positive people who participated in the study had ear problems. As the ear is something internal and close to the brain, he says that tinnitus must be taken very seriously indeed.

Spector says that tinnitus, for some people, can sound like: Ringing, buzzing, humming, hissing, throbbing, music or singing, or whooshing.

New plant-based COVID vaccines

A new plant-based COVID vaccine has been found to be nearly 70 per cent effective against new Coronavirus variants (India Today, May 6, 2022). The vaccine is grown inside a native Australian plant related to tobacco. It has been made by a Canadian firm named Medicago and has been approved in Canada for people of age 18 to 64.

Scientists insert bacteria containing the SARS-CoV-2's genetic code into the plant, Nicotiana benthamian. The plant then starts producing its own coronavirus-like particles or CoVLP. These particles are extracted and combined with an immune-boosting additive called adjuvant to develop the final vaccine, called CoVLP+AS03. The study published in the New England Journal of Medicine (NEJM) says that the vaccine is 69.5 per cent effective against symptomatic infection and 78.8 per cent effective against moderate-to-severe disease.

15,000 pandemics may emerge

According to a recent report, 15,000 potential pandemics may emerge in the next 50 years (The Mint, April 30, 2022). This is the likely result of mammals transmitting viruses to other mammals. Such events of viruses (or other pathogens) jumping the species barrier are known as spillover events or simply spillovers. And diseases resulting from such spillovers are known as zoonotic diseases.

The causes for spillover are quite complex. But one major triggering factor is climate change. The worsening climate change and global warming will cause shifts in wildlife habitats leading to close encounters between species capable of exchanging pathogens. Studies of relationship between global warming and zoonotic diseases have been published in a recent issue of the leading journal Nature.

How can climate change affect the probability of zoonotic diseases?

Some likely reasons include:

As temperature rises, many animal species will move to cooler regions where they will meet several other new species leading to new spillover events. Increased virus spillovers will trigger more viral outbreaks like COVID-19.

Hotpots of viral spillovers will be regions that are rich in biodiversity which are also densely populated (parts of Africa and Asia). This process has probably begun and will continue unless we concertedly take initiatives to mitigate carbon emissions.

Bats are considered to be major reservoirs of viruses and will continue to be main agents of viral transmission irrespective of climate change.

If we have to ensure the survival of humankind, we must act in concert to drastically cut down carbon emissions, stop deforestation, carry out urgent Afforestation projects and conserve other carbon sinks. Colin Carlson, the study's co-author said that "climate change is creating innumerable hotspots of future zoonotic risk-or present day zoonotic risk."


Nobody knows for sure how COVID-19 will end

There may be three scenarios for a possible COVID ending: medical, political, and social (Business Standard, Mar. 10, 2022). Nobody knows for sure how COVID-19 will end. But past epidemics can provide some clues. According to Dr Erica Charters, University of Oxford, there could be different types of endings that may not all occur at the same time.

A medical end may happen when the disease retreats. A political end will take place when the government stops preventive protocols. A social end will occur when the people (society) move on despite the pandemic. There is ample reason to believe that the COVID end is near in the United States. Sixty-five per cent Americans are fully vaccinated, and about 29 per cent are both vaccinated as well as administered booster doses.

We may look at the trajectories of some past pandemics. The 1918 Spanish flu killed about 500 million people globally and came in three waves. Another flu pandemic of 1957 killed about 116,000 Americans and another pandemic in 1968 killed 100,000 more. Another flu pandemic in 2009 didn't turn out to be as serious as it was anticipated; it fizzled out quite soon and quite unexpectedly.

WHO declared COVID-19 as a pandemic on March 11, 2020 and it has raged across the glove for 2 years now. The global health agency will monitor the global decline in cases, hospitalizations and deaths before deciding if the international health emergency is over. Covid cases are waning in US and dropped globally by 5% in the past week. However, cases are seen rising in some other places such as the UK, Hong Kong, and New Zealand.

Poor people in many countries still are in dire need for vaccines and medications. In Latin America and the Caribbean alone, over 248 million people have not had their first vaccine dose. Countries will low vaccination rates will still see surges in illnesses, hospitalizations and deaths. Dr Ciro Ugarte, Director of health emergencies, PAHO says that we're still not out of the pandemic and we still need to tackle this raging pandemic with a great lot of caution.

Hence, we must not let our guards down and we must still strictly observe the non-pharmaceutical interventions such as the use of face masks, physical distancing, and hand hygiene.

In view of the looming threat of new COVID surge, Manipur must remain alert at all cost to prevent the spread of any form of new pandemic and reduce the number of deaths in any eventuality.

Hospitals and pharmacies in Manipur must stock up Paxlovid drugs for use in unvaccinated, elderly, and high risk people in the state as and when required.

State must continue stringent monitoring of arrival of COVID sub variants, genome tracking and sequencing, testing, contact tracing and vaccination of booster shots to all eligible people, and proper deaths audits. There is also a need to enhance the ratio of RT-PCT to Rapid Antigen Testing (RAT). Healthcare workers and officials must continue to spread awareness about the pandemic.

The state government must continue to ensure improved healthcare infrastructure and healthcare provisions such as medical oxygen plants, tankers and cylinders; steroids, antifungal drugs, oxygen concentrators, ventilators, oximeters, masks, PPEs, sanitizers etc.

There is also a need to maintain special taskforce to fight possible new wave and a separate taskforce for pediatric COVID Special provisions for kids such as pediatric hospitals, wards, and ICUs, pediatric oximeters, concentrators, and ventilators and strengthening of staff such as pediatricians and pediatric nurses and paramedical workers are a must.

The state must religiously follow the protocol of 'test, track, and treat' for months to come. If possible, the public health authorities must take steps to prevent large gatherings such as weddings and death ceremonies, music concerts, and large meetings.


First published:


climate changecovid-19 updatenew vaccineSARS-COV-2COVID Sub Variantsdisease emergence

Debananda S Ningthoujam

Debananda S Ningthoujam

The author teaches and studies microbial biochemistry and biotechnology at Manipur University


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