Weeks after the World Health Organisation (WHO) declared that Covid-19 was no longer a Public Health Emergency of International Concern, the WHO Director-general Dr Tedros Adhanom Ghebreyesus at the 76th world health assembly said that the threat from Covid-19 or from other pandemics was not over.
He said, “The end of Covid-19 as a global health emergency is not the end of Covid-19 as a global health threat. The threat of another variant emerging that causes new surges of disease and death remains. And, the threat of another pathogen emerging with even deadlier potential remains,” he said.
Dr Tedros said that the meeting on pandemic preparedness during the assembly must be utilised to chart a path forward. He said, “We cannot kick this can down the road. If we do not make the changes that must be made, then who will? And if we do not make them now, then when? When the next pandemic comes knocking – and it will – we must be ready to answer decisively, collectively and equitably.”
Can Covid-19 still mutate to have a deadlier variant?
Over three years after the World Health Organisation raised its highest level of alarm for the novel coronavirus disease Covid-19, the intra-government organisation in May first week said that it no longer was a public health emergency of international concern.
While the infection led to waves of infections and deaths in all countries – three in India – the numbers have been on decline. With people gaining immunity against the infection through natural infection or vaccination, the virus has been leading to fewer cases of severe disease and death. However, it continues to be in circulation.
Many people are still getting the infection – India saw a surge in infections in April – sometimes even without symptoms. Mutations are random and the more a virus transmits, the more mutations it gathers. And, mutations that can cause deadlier infection might arise at random. Experts say, although the likelihood is small, it may happen. This is the reason they say that surveillance for the virus should be continued.
Dr RR Gangakhedkar, former head of epidemiology and communicable diseases at the Indian Council of Medical Research, had previously told The Indian Express that there is always a likelihood of Sars-CoV-2 mutating into a new coronavirus with transmission between humans and animal reservoirs.
“The virus continues to have reservoirs in animals – even say household rodents – so the possibility of transmission back to humans can never be ruled out. That will, however, lead to different mutations that could be beyond Sars-CoV-2. It will remain in the coronavirus family only, of course,” he said.
Why do pandemics happen?
While infections have been jumping from animals to man, a more globalised world with ease of travel makes it likely for such an infection to spread to a large number of populations and countries. Billions of people undertake air travel each year, providing a great mechanism for infections to spread.
There has also been an increase in urbanisation. Urbanisation not only leads to a large number of people living in close proximity – allowing an infection to spread – but it also leaves many without proper sanitation, housing, and healthcare providing a fertile ground for spread of infections.
Travel and density of population has played a role in previous pandemics as well. The Spanish Flu of 1918 happened towards the end of World War I. It spread rapidly among troops living in congested, overcrowded camps with poor hygiene and was then transported by them to the cities and countryside. The deadliest pandemic in recorded history Black Death is also thought to have come to Europe with rats that were aboard trading ships.
How has climate change impacted outbreaks and pandemics?
There are several ways in which climate plays a role in outbreaks and pandemics.
First, deforestation and encroachment of habitats of other animals has brought the humans and animals closer. Increased human-animal interactions give an infection more opportunity to learn how to jump over from their animal reservoir to humans. The pathogen that led to the 2003 SARS outbreak likely came from palm civets and the pathogen that causes MERS came from dromedary camels. Sars-CoV-2 that causes Covid-19 is also thought to have jumped from bats to humans.
Second, the climate itself may change the habitats of the disease-carrying vectors. Take for example, the mosquitoes that cause dengue in India. The disease earlier did not occur in colder, hilly states. The geographical range of dengue in the country expanded from just eight states in 2001 to all states by 2022. Or, scrub typhus that was usually seen only in forested, hilly regions but is now reported every year from cities like Delhi.
Third, climate change also leads to extreme weather events that can displace people and force them to live, even temporarily, in congested encampments without proper hygiene.
What are the pathogens likely to lead to the next pandemic?
Much before Covid-19 happened, there was research suggesting that a novel coronavirus was likely to cause the next pandemic. This is because coronaviruses are one of the pathogens that have pandemic potential – bacteria, viruses, or microorganisms that are highly transmissible capable of spreading unchecked amongst humans and highly virulent capable of causing severe disease and death.
The World Health Organisation has a priority list of pathogens that are likely to pose the greatest threat to public health and don’t have adequate drugs and vaccines against them. This list acts as the basis for prioritising research for developing diagnostics, drugs, and vaccines for these diseases.
Other than Covid-19, the list includes Crimean-Congo haemorrhagic fever (a tick borne fever that can lead to internal bleeding), Ebola virus disease and Marburg virus disease (severe and often fatal viral infection that can lead to heavy bleeding), Lassa fever (another viral fever that leads to bleeding like ebola), Middle East respiratory syndrome coronavirus (MERS-CoV) and Severe Acute Respiratory Syndrome (SARS) (cousins of the Sars-CoV-2 virus that caused Covid-19), Nipah and henipaviral diseases (a viral infection usually transmitted by fruit bats that may lead to brain swelling), Rift Valley fever (mainly an animal disease but can sometimes be transmitted to humans and some forms of the infection can cause eye lesions, brain swelling, or internal bleeding), and Zika (may cause microcephaly or smaller brain and other congenital malformations in foetus when pregnant mother is infected).
Other than that the list also includes ‘Disease X’ that represents “a serious international epidemic could be caused by a pathogen currently unknown to cause human disease.” In which case, the research focus would be to develop platform technologies that can be adapted for a new infection.
There is a need for countries and healthcare systems to prepare for such future pandemics. This can be done by putting in place a surveillance system that can keep an eye on ups and downs or changes in disease pattern or symptoms in a population and quickly alert the public health machinery. A one-health surveillance that can track outbreaks not only in human population but also in animal populations that may jump over to humans might help.
Government also have to work towards reducing risks of getting an infection by ensuring sanitation and hygiene. Providing clean drinking water and nutritious food can help.
And, there is a need to keep the health systems ready for a health emergency. This will include not only availability of equipment and trained manpower but also having systems to ensure that any new medical countermeasure – diagnostic, drug, or vaccine – can quickly be manufactured and made available.