Delta Variant
WHO has recently launched a new nomenclature for the SARS-CoV-2 variants of concern (VoC) and variants of interest (VoI) circulating across the globe. A coronavirus mutant is called a VoC if it has one or more properties of increased transmission, enhanced tendency to cause severe disease, reduced detection in diagnostic tests, higher resistance to currently used vaccines, increased tendency to develop vaccine-escape variants etc. If the variant lacks these properties, it would be dubbed simply as VoI.
The World Health Organization (WHO) is currently monitoring the trajectory of four variants of concern around the world. These 4 VoC are:
- B.1.1.7 (alpha variant, earlier called Kent/UK mutant).
- B.1.351 (beta variant, earlier called South African variant).
- P.1 (gamma variant, previously named Brazil mutant).
- B.1.617.2 (delta variant, formerly called Indian double mutant).
The mutant first detected in India-B.1.617-has now been shown to have 3 sub-lineages: B.1.617.1, B.1.617.2, and B.1.617.3. Of these, the B.1.617.2 variant, now popularly called delta variant has the highest transmissibility and is thus the most concerning for India as well as the world. B.1.617.1 is called the kappa variant and has been shown to cause a small percentage of infections in India but the third sub-lineage B.1.617.3 is not significant in terms of its ability to cause infections.
A study conducted by BHU and CCMB (a CSIR Institute based in Hyderabad) found that the delta variant is the most prevalent strain in India now and is possibly behind the tsunami of COVID second wave in India (The Print, June 5, 2021). For this study genome sequencing was done for 130 samples, and 36 per cent of the samples was associated with the delta (B.1.617.2) strain. The study team found at least 7 coronavirus strains circulating in and around Varanasi. It was concluded that the delta strain seems most robust and is now overtaking all other variants but it was also emphasized that we must be on the lookout for other emerging variants before it can spread and trigger a deadly outbreak. Another study by INSACOG found that incidence of B.1.617 and its sub-lineages was the highest in UP (81.8 per cent), followed by Gujarat (77.4 per cent) and Jharkhand (67.2 per cent). It's quite possible that the delta and other sub-lineages of B.1.617 may be the predominant variant in other Indian states including Manipur; this can only be ascertained if genomic surveillance is extended and intensified in states where such studies are currently lacking. Another worrisome development is that the delta Covid variant has now spread to UK, Australia and may be other parts of the world e.g. Vietnam (TOI, June 4, 2021). The delta variant has been found to be 50 per cent more transmissible than the alpha variant (the erstwhile UK strain). It has now become the dominant strain in the UK. Because of this highly transmissible variant, warnings of incipient third wave in the UK are now reported and some experts have suggested postponing of the easing of lockdown restrictions in the UK that's supposed to begin on June 21, 2021 (The Guardian, June 4, 2021). Since the last few weeks, 75 per cent of new COVID cases there is caused by this variant (New Scientist, June 1. 2021). Prof Ravi Gupta, Indian-origin scientist based in the University of Cambridge has also advised the government to go slow on easing restrictions in the UK in view of the surging delta variant which is much more transmissible.
Vaccinations
India's vaccination rate is much lower relative to several developed and even some developing countries. According to data available till June 4, 2021 (https://ourworldindata.org; last accessed June 5, 2021), Seychelles tops the chart of percent fully vaccinated population (65.1 per cent), followed by Israel with 59.4 per cent. India (3.2 per cent fully vaccinated) lags far behind US (40.9 per cent) and UK (39.5 per cent). Among large developing countries, Brazil (10.7 per cent) is far ahead of India (3.2 per cent). Vietnam though having an excellent track record of controlling the spread of COVID-19, has poor vaccination speed so far with only less than 0.1 per cent of its population fully vaccinated.
Only 5.8 per cent of the world's population is fully vaccinated, far short of the number needed to achieve herd immunity against COVID-19.
A Lancet study (Lancet, June 3, 2021) recommends shortening the gap between the two doses of the vaccine as most vaccines e.g. Pfizer, was shown to be less effective against the delta strain of SARS-CoV-2, particularly after the first jab. It was found that in people who had been vaccinated with 2 doses of the Pfizer vaccine, the levels of neutralizing antibodies were more than 5 times lower against the delta variant when compared to the original (Wuhan) strain, against which the current vaccines were designed. The antibody response was much lower in people who had been inoculated with just 1 jab. After a single dose of the Pfizer vaccine, 79 per cent had a significant antibody response against the original strain; this level fell to 50 per cent for alpha strain and 32 per cent for delta strain and 25 per cent for the beta strain, the variant first observed in South Africa.
Antibody levels also decrease with age against all variants and with more time elapsed after infection or vaccination. The scientists involved in the study noted that the most crucial thing is to ensure that protection by vaccines remain high enough to keep as many people out of hospital as possible. The study also suggests to quickly administer 2nd jabs to those who have received their first vaccine dose and provide booster doses to those whose immunity may not be high enough against the coronavirus variants (elderly people with and without co-morbidities).
Strategies for the third wave
An IIT Delhi study has depicted 4 possible scenarios for a possible third wave in Delhi (The Hindu, June 4, 2021). However, it must be pointed out that when, where and how seriously would the third wave hit India has not been clearly delineated by any of the COVID modeling studies. Even though the COVID curve is dipping in Delhi now, the IIT study suggests four possible outcomes: about 28,000 daily cases (scenario 1, same as 2nd wave), around 36,000 daily cases (scenario 2, 30 per cent more than 2nd wave), about 45,000 daily cases (scenario 3, 60 per cent more than 2nd wave), and about 15,000 cases per day (scenario 4, best case scenario).
Accordingly, the Kejriwal government has constituted a taskforce to suggest measures to face the possible third wave e.g. establishing PSA oxygen plants, buffer stocks of oxygen tanks and D-type cylinders and ICU beds etc. In addition, special measures were suggested to tackle possible pediatric COVID cases in the third wave. These included provision of pediatric ICUs and oxygen beds for children, pediatric masks and gadgets such as oximeters, concentrators and ventilators suitable for children, more pediatric wards, pediatricians, and specially trained nurses and initiation of awareness campaigns for pediatric COVID.
Certain measures would help prevent, ward off, or mitigate the third wave. One is to massively speed up vaccinations. Another is aggressive genomic surveillance to monitor the trajectory of delta and other COVID variants across the country to ascertain which variant is surging where and catch any new variant early before it leads to a deadly local outbreak. R Sukumar, Editor-in-Chief, Hindustan Times has another two interesting suggestions (HT, June 3, 2021). One is to link the stringency of standard SOPs (3 Ms, 3 Ws, as mentioned in previous columns) in a district to the ratio of the population that has been vaccinated. Another is about deciding when and where to ease to ease lockdowns; he suggests a possible benchmark: 5 per cent positivity rate or less for two weeks combined with vaccine coverage of a minimum of 20 perc cent of eligible population (18 years and above) to permit easing of restrictions in any locality.
Possible measures for Manipur
We need to assume that there may be a third wave in Manipur too. Even if that may turn out to be a wrong anticipation, it's better to err on the side of caution. Accordingly, we must initiate measures to squarely face a possible third wave in our state.
These may include:
- Speeding up vaccinations in a big way.
- Genomic sequencing of a subset of positive cases and surveillance of the variants including the delta variant: which COVID strains are there in Manipur, where are they, and where are they moving towards.
- Boosting up healthcare provisions such as medical oxygen plants, tankers and cylinders; steroids, antifungal - drugs, oxygen concentrators, ventilators, oximeters, masks, PPEs, sanitizers etc.
- Strengthening of healthcare infrastructure such as construction of new COVID hospitals.
- Provision of more COVID care centres (CCCs), more Covid beds and ICUs in existing hospitals
- Constitution of a special taskforce for the third wave; a separate taskforce for pediatric COVID is also highly recommended.
- 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 etc.
(The views expressed are the writer's own)
