Countries in Africa registered 94 per cent of all malaria cases and deaths that took place globally in 2019; India saw the largest drop in cases in WHO’s South-East Asia Region
Malaria experts told Down To Earth October 7, 2021 that India should prepare to get the first vaccine against the disease so as to immunise people in select states, despite its declining disease burden. The World Health Organization (WHO) has recently approved the vaccine.
India contributed to the largest drop in cases in the WHO’s South-East Asia region — six million from approximately 20 million. This is according to the WHO’s latest World Malaria Report.
“But the cases can flare up any time. Malaria is sensitive to rain, precipitation and other such weather conditions that have been erratic,” PL Joshi, former head of National Vector Borne Diseases Control Programme, told DTE.
He also said insecticides sprayed to get rid of the malaria parasite as well as mixed into bed nets were a source of environmental pollution.
“The nets are a big problem as they are treated with insecticides treated with polyester. It is an environmental hazard and their disposal is a big problem,” Joshi said. Vaccines were required in India to get rid of these, he added.
However, he and two more experts DTE spoke to, were of the unanimous view that a pan-country rollout of the vaccine would not be necessary.
All three of them said there were some high disease-burden states like Jharkhand, Chhattisgarh, Odisha, Madhya Pradesh and Meghalaya that would have to be targeted for such a programme.
What is the vaccine?
The vaccine could prove to be a key tool in the anti-malaria programme, a disease that killed 409,000 and sickened 229 million in 2019, according to the WHO report.
Countries in Africa registered 94 per cent of all malaria cases and deaths that took place globally in that year. Children aged under five years accounted for 67 per cent of all malaria deaths globally.
The anti-malaria vaccine, Mosquirix, has been developed by pharma major GlaxoSmithKline (GSK). It has been termed as partially effective due to low efficacy.
The clinical trials were conducted among 15,000 children aged 5–17 months, who received four doses of the vaccine. It prevented approximately 4 in 10 (39 per cent) cases of malaria over four years of follow-up and about 3 in 10 (29 per cent) cases of severe malaria.
This indicated that the immunity waned after a certain period. These trials were conducted in eight African nations.
Pedro Alonso, head of WHO’s global malaria programme, said that though the vaccine was partially effective, it was completely safe. He was speaking during a discussion on the malaria vaccine October 7.
This was demonstrated in the trials and the three pilot studies launched in Kenya, Malawi and Ghana, where another 800,000 children had been inoculated.
Vaccine expert, Gagandeep Kang, a virologist at CMC-Vellore said it was initially observed after trials that there was a slight increase in neurological complications after vaccine administration.
But large-scale pilot studies showed that there were no side-effects. “This would have given the confidence to WHO to give an unconditional global recommendation for the vaccine,” she said.
Kang and Indian Institute of Science Education and Research-Pune’s Vineeta Bal also pointed out that merely looking at so-called partial efficacy figures would be unscientific, considering the disease burden, especially in Africa.
“In some countries of Africa, children get malaria eight times a year. If the vaccine can reduce even the number of these episodes, it can be a great public health advantage,” Kang said.
She added that even vaccines against rotavirus (which causes diarrhoea) and poliovirus have relatively low efficacy but are still a part of routine immunisation programmes.
Bal also pointed out that one has to look at disease alleviation as a public health measure rather than looking at the efficacy number in a vacuum.
Long journey to development
Mosquirix is incidentally the first vaccine to be developed against any parasite. Experts point out that it is relatively easier to develop vaccines against viruses (some of them), followed by bacteria and parasites.
Alonso agreed with the contention that it was most difficult to develop a vaccine against a parasite. But he stated that the failure to develop an anti-malaria vaccine represented a ‘market failure’.
“Malaria is a disease of the poor and it causes poverty. The industry thought why should we invest in it,” he said.
However, he pointed out that despite a partial efficacy, if WHO had approved a vaccine, it was a clear signal to the market that it should come and make more. “We are serious about it,” Alonso said.
GSK has so far made a commitment of 15 million doses annually, which may not be enough if the demand soars. India’s Bharat Biotech Intl Ltd, which has produced the vaccine Covaxin for the novel coronavirus disease, would produce antigen for the malaria vaccine as part of technology transfer.
There are many more vaccine candidates in the pipeline. But Mosquirix and those in the pipeline are supposed to provide protection against malaria caused by Plasmodium falciparum and not Plasmodium vivax.
More than 90 per cent malaria cases are caused due to Plasmodium falciparum. “We also have to pay attention towards Vivax as it can’t be ignored,” Alonso said.
Alonoso called upon global funding agencies and countries to invest in financing the vaccine now that it had been approved. This would ensure adequate availability of the doses.
“Not only financing, but what is required is developing location-wise tool kits smartly. For instance, providing it to developed countries would be pointless since the incidence is very low and maybe drugs are enough to do the job there,” Bal said.
Malaria cases in the WHO’s Eastern Mediterranean Region reduced by 26 per cent, to about five million in 2019, from about seven million cases in 2000.
The WHO’s Western Pacific Region had an estimated 1.7 million cases in 2019, from three million cases in 2000, a decrease of 43 per cent. In the WHO Region of the Americas, malaria cases reduced by 40 per cent (0.9 million from 1.5 million).
What about waning immunity after 5 years? “We would learn on the job. The vaccine has just been approved after all,” Bal said. She added that it was a challenge that remained to be tackled.
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