Need to reorient strategy to combat pandemic despite lull in COVID transmission
There is no room for complacency. All precautions must be taken before the second wave arrives in Manipur. State must also ensure that those suffering from post COVID health complications are properly treated.
From analysis of the data made available through the various government sources on COVID-19 in Manipur, one can safely conclude that the there is a hiatus in the transmission and mortality in January 2021. It perhaps heralds a good omen. Starting from December 2020, the positivity rate as well as mortality rate decreased, slightly in December but significantly in January despite concern that the winter may see sharp increase. There is, however, a drop in the number of test being carried out as seen from Table-1, but the positivity rate shows a reduction. From an average test of 1,854 per day during December from the high of 3,558 per day during October the number of average test per day fell to 1,203 during January. 2021. The positivity rate fell to 2.36 per cent as compared to 5.47 per cent and 9.57 per cent in December and November, 2020 respectively. Similarly, January saw a sharp decline in the death rate due to the disease. The mortality rate fell below 1 per cent to 0.84 per cent as compared to 1.66 per cent and 1.40 per cent in November and December respectively. For Manipur, the worst month was November 2020.
Table I: Data on the tests, positive cases, death and discharged
From the computed weekly data of January 2021, it is clear that the positivity rate show a gradual decline with time though the mortality rate fluctuated. The absolute number of positive cases and deaths had shown a sharp decline in January 2021, and the cumulative positive cases remains below 30,000. The number of active cases is 144 as on January 31 and the number of hospitalisation is only a handful. On the other hand, nearly 4,000 healthcare providers have been vaccinated and the next phase of vaccinating the other frontline workers will be starting. Thus, there is a slim chance that Manipur may beat the second wave. It may be appreciated that the sooner the second wave comes the less virulent it is. If the second wave comes much later it is worse than the first wave as seen in many parts of the globe. This is not unexpected as the antibody to the virus does not last long; for about six-eight months. Therefore, complacency should not settle and there is a need to ensure that the vaccination program is enlarged so that more people are protected within a short span of time to attain herd immunity. Intensification of the vaccination programme is the need of the hour and besides the two vaccines granted EUA in India, other vaccines also need to be explored. Once the single dose J&J vaccine is approved, use of it will greatly benefit the programme.
Table II: Data on the tests, positive cases, death and discharged in January 2021
It must, however, be emphasised that vaccination is not the panacea to the pandemic as the protection do not last a year and the efficacy rate is in the range of 70-90 per cent. Further, on many conditions, vaccination is contraindicated. Manipur had not seen any fatality on vaccination and in fact complaints of side effects is much lower compared to other parts of the country and most of them recover without medical intervention. With newer more virulent strains popping up here and there, the challenge is much more than anticipated. There is always a question of whether the vaccines available will be able to protect from the newer strain and research is going on and claims are that some vaccines provide protection to at least the UK strain.
Now multiple variants of SARS-CoV-2 are circulating globally. More than 12,000 mutations have been detected but most of them die out as it does not provide any advantage to the virus. However, certain variants which affect the spike proteins have shown to be more easily transmitted. The UK strain known as B.1.1.7, the South Africa strain B.1.351 and the Brazil strain known as P.1 are causes of serious concern. The B.1.1.7 has a mutation in the receptor binding domain (RBD) of the spike protein where asparagine (N) is substituted by tyrosine (Y) and the short form is N501Y. This strain also carries other mutations, the significant ones being 69/70 deletion which may lead to conformational change in the spike protein, mutation at P681H near the furin cleavage site, etc.
The South Africa variant B.351 has multiple mutations in the spike protein, including K417N, E484K and N501Y. It does not however have the deletion at 68/70 as in the UK strain. The Brazil strain P.1 which was first detected in Japan among four travellers from Brazil contains three spike protein mutations in the RBD that is K417T, E484K and N501Y. In the Manaus region of Brazil P.1 variant constitute 42 per cent of the specimens sequenced and it was hinted that in this region about 75 per cent of all reported cases are with this variant.
Some of the potential consequences of emerging variants are: Ability to spread quickly with evidence that one mutation D614G provides increased ability to spread; ability to cause either milder or more severe disease in people as in the case of B.1.1.7 where there is increased risk of death; ability to evade detection by specific viral diagnostic test but for now this is not an issue with RT-PCR as it has multiple targets and one mutation will have no impact on the efficacy of RT-PCR test; decreased susceptibility to therapeutic agents such as monoclonal antibodies; and ability to evade natural or vaccine induced immunity as in both the cases it produces polyclonal response that target several parts of the spike protein and only when there are multiple mutations in the spike proteins can the virus evade the immunity formed by vaccination or natural infection.
For those not involved in biochemistry, the letters in identifying the mutants will be confusing. For easy reference single or three letter codes were developed for the various amino acids. The figures indicate the location. D represents aspartic acid, E glutamic acid, G glycine, H histidine, K lysine, P proline and T threonine, besides N and Y which was indicated above. N501Y means that at position 501 asparigine is replaced by tyrosine.
Why we need all precaution is that UK strains have been detected in India and other strains also may be circulating. There are also reports that the UK variant had undergone further mutation and Covishield is less efficacious against the South Africa strain, though more study is required to confirm. Further, immunity develops two week after application of the booster dose which in turn was given four weeks after the first shot. In other words, immunity develops one and half month after the first jab. Further, all those who receive the shots do not develop the immunity as the efficacy of the vaccines ranges from 70 to 90 per cent. And very little is known about the efficacy of the vaccines against emerging variants.
Studies are being conducted whether the disinfectants and sanitisers prescribed for the original strain is effective against the emerging strains as also the vaccines and the therapeutic drugs. In the meantime, to protect against infection, the standard precautions of proper wearing of mask when with others, washing hands with soap and clean water frequently for at least 40 seconds or rubbing with alcohol based hand sanitisers for at least 20 seconds, maintaining physical distance of 2 metres from others, observing respiratory etiquette, avoiding crowd, interacting with people outdoors and keeping doors and windows open as far as practicable must be followed by all including those who have been infected and recovered and those who have been vaccinated.
The state must also ensure that those suffering from post COVID health complications are properly treated as one in eight who was seriously ill from COVID-19 succumb to post COVID complications as per a report. The lull in the transmission is not a period for rejoice and complacency but a time to reorient our strategy to combat the disease before the second wave arrives.
(The views expressed is the writer's own)
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