Mutations, concerns about vaccine immunity
A healthcare worker conducts a polymerase chain reaction Covid test on a traveller at OR Tambo International Airport in Johannesburg on November 27 after several countries banned flights from South Africa following the discovery of a new variant called omicron. — Agence France-Presse/Phill Magakoe
By Zubair Khaled Huq :
THE World Health Organisation has announced that a new Covid strain was detected in South Africa and has named it the omicron variant. The new Covid variant has at least 30 mutations in the spike protein. It can change the spike protein and evade the immunity given by the vaccine. The new variant, first found in South Africa, has already restricted movements and a global ban has been on the cards. It has the potential of developing immune escape mechanisms. As many vaccines work by forming antibodies against the spike protein, change in the spike protein can make many vaccines inefficient or lose potency soon. The presence of the spike protein facilitates entry of the virus in the host cell. A critical evaluation for the vaccine accuracy has to be tested and the vaccine has to be effective, but how or which one is elusive. Otherwise, only complacency of dose completion may entail dire consequences.
We must ask everyone to religiously follow Covid behaviour, not to let guards off. The virulence and immune escape have to be tested for all vaccines so that the need for booster dose, increasing potency, can be considered. In the past week, the heavily mutated Covid variant was identified, rapidly labelled a ‘variant of concern’ by the World Health Organisation. It has so far been detected in several countries. Yet, in this early stage, in the absence of definitive facts and when there is a danger of both under-reacting and over-reacting, the vaccine companies have to act.
Our response is to test everyone coming in from abroad, isolate all omicron contacts, speed up boosting and bring back compulsory mask wearing in public places. We are slipping down the barrel, throwing our guards off. Masks are not seen as even a few months before. People need to be forced to wear masks. People appear oblivious to the fact that even after two doses of vaccines, people are not immune against Covid-19 and may contract the new strain as it passes from human to human. One cannot be certain that this virus has not entered Bangladesh. If a virus is good at spreading, it eventually will slip through. And it has the potential to spread here too. Cases of Covid-19 have been climbing except for a lull over the October half term. But if the delta variant can spread here and the omicron variant combines, resulting in a faster transmission with some ability to evade immunity, it too has the potential to circulate.
There are important scientific issues that need analysed and on top of the list is what happens when omicron meets high levels of immunity. The answer, for better or worse, will dictate what happens next. The vaccines are used by different pharmaceutical companies to train the body to attack the spike protein on the virus and that spike is from the original variant that broke out in Wuhan, China. Most vaccines focus on ‘teaching’ the body to generate antibodies that neutralise the spike protein of the virus that latches on to human cells. But mutations of many new variants are in regions of the spike protein that antibodies recognise, raising concern that this may impact the vaccine efficacy.
The World Health Organisation’s technical lead on Covid-19, said: ‘We don’t know very much about this yet. What we do know is that this variant has a large number of mutations. And the concern is that when you have so many mutations, it can have an impact on how the virus behaves.’ ‘We need to understand that the more this virus circulates, the more opportunities this virus has to change, and the more mutations we will see,’ it said, stressing the importance of driving transmission down. Even though some of the genetic changes appear worrisome, it was unclear if the new variant would pose a significant public health threat. Some previous variants, like the beta variant, initially concerned scientists but did not spread very far. Instructions have been issued to tighten screenings at all entry points, including airports and land ports.
Although epidemiologists say that travel curbs may be too late to stop omicron from circulating, many countries, including the United States, Brazil, Canada, European Union countries, Australia, Japan, South Korea and Thailand, have announced bans or restrictions travel to and from South Africa. More countries, including Indonesia and Saudi Arabia, have imposed such curbs. The new variant has also thrown a spotlight on huge disparities in vaccination rates around the world. Even as many developed countries are giving the third-dose boosters, fewer than 7 per cent of people in low-income countries have received their first Covid shot, according to medical and human rights groups. The new mutations, after having been detected in South Africa, have since been detected in Belgium, Botswana, Israel and Hong Kong. At least 59 people in these countries are confirmed to have contracted the variant.
The big question is: will the existing vaccines work? Scientists are concerned by the number of mutations and the fact some of them have already been linked to an ability to evade existing immune protection. These are theoretical predictions though, studies are conducted to test how effectively antibodies neutralise the new variant. Real-world data on reinfection rates will also give a clearer indication on the extent of any change in immunity. Scientists do not expect that the variant will be entirely unrecognisable to existing antibodies, just that existing vaccines may give less protection. So, the crucial objective that remains is to increase vaccination rates, including booster doses for at-risk groups. Will the variant cause more severe Covid-19? There is no information yet on whether the variant leads to a change in Covid symptoms or severity. This is something South African scientists will be closely monitoring. As there is a lag between infections and more serious illness, it will take several weeks before any clear data are available. At this stage, scientists say that there is no strong reason to suspect that the latest variant will be either worse or milder.
The World Health Organisation says that early evidence suggests that the omicron variant could pose an increased risk of reinfection and that some of the mutations detected in the variant were concerning. So even if one is vaccinated, there is every possibility of further infection with deadly variant any time. So only travel restrictions are not enough. Mask wearing has to be re-emphasised to keep the virus at bay. We have to adhere to continuous surveillance. The scientific community is worried as they fear that the new strain could fuel outbreaks in several countries and cripple health systems once again.
Dr Zubair Khaled Huq is a public health specialist. Courtesy : New Age
