By Dr Edward Nazareth
Jun 26: The war between Covid-19 virus and mankind seems to be not ending. As there are no effective anti-viral medicines, the vaccines are the only hope to face the pandemic. Fortunately the vaccines are prepared in an unprecedented speed and are used on emergency basis. The vaccines have helped in controlling the spread of the disease. Though these vaccines could not prevent re-infection in all, it is now proven beyond doubt that the existing Covid-19 vaccines control the seriousness of the illness and can prevent deadly complications in most of the people who are infected even after vaccination.
The Covid-19 virus is not receding. It is mutating regularly and by each mutation it is gaining strength to infect more number of people. The mutation can lead to alterations in the virus’ surface proteins or antigens. Most of the Covid-19 vaccines are prepared using the surface antigens of the virus. If the virus could change its surface antigens, then the vaccines will not be effective. Is the Covid-19 virus attempting that?
‘Delta’ to ‘Delta Plus’
The most recent mutation is ‘Delta-plus’. It is a further change in the earlier mutated strain ‘Delta’. The ‘Delta’ variant, also known as ‘Indian variant’ was first detected in India in December 2020. Though there were several variants of Covid-19 during the second wave in India, the most predominant variant found during the second wave was ‘Delta variant’. This variant was also reported to be one of the major drivers of the second wave of Covid-19 in India.
The ‘Delta variant’ has spread in many countries and caused havoc there. The ‘Delta variant’ has now become the dominant strain in the UK, currently accounting for more than 90% of cases there. In the US too, the number of Delta variant cases is rapidly rising, up from 10% of the total Covid-19 cases last week to 20% this week. It is reported that the delta variant accounts for more than a third of new cases each day in the US.
The Israeli health ministry re-imposed the rule that the masks to be worn in enclosed public places on 25th June 2021 following a surge in new Covid-19 cases which dropped 10 days ago. Israel reported more than 100 fresh cases per day for the past four days and this surge is attributed to highly contagious ‘Delta variant’.
Russia is also facing a surge in COVID-19 cases and the authorities are blaming the highly infectious Delta variant with deaths linked to the virus hitting a new record in Moscow on 25th June 2021.
The highly infectious ‘Delta variant’ has now mutated into much more potent ‘Delta Plus’ variant.
Why Covid 19 mutates?
Mutation is the property of a virus to undergo changes when it multiplies. The basic structure of virus is the combinations of different amino acids placed at particular places. The spike protein, the surface protein of Covid-19 virus is composed of a linear chain of 1,273 amino acids, neatly folded into a structure. They are like bricks placed in a proper order to build a structure. As the virus multiplies, it alters some of its amino acids, change their position resulting in new strains. (Some bricks are interchanged so that the structure remains the same, but look alters). These new strains may be stronger than the original or at times weaker. During the process of mutation, some strains die out, while the more effective ones, which spread efficiently, survive.
The Covid-19 virus also has mutated several times. The virus that has spread around the world is not the same as the virus that emerged in Wuhan province of China in late 2019. This is because, like many other viruses, Covid-19 virus has changed in its genetic structure through mutation. Mutation is a blessing from Mother Nature to many micro-organisms like viruses so that they survive facing the ‘situations that might eliminate them otherwise’! We have invented vaccines so that the virus may not multiply in a vaccinated person. To overcome this hurdle, the virus has to change its genetic structure- that is exactly what Covid-19 virus has been doing.
But all the mutations may not help the virus to thrive. Many of the mutations are silent: they do not alter the function of the virus in any way, and they don’t result in changes in disease severity or immune responses. Of those that are not silent, many are damaging to virus functions and result in non-viable viruses, and therefore do not survive into a new generation of viruses. It is known that of the 24 possible mutations of Covid-19 virus, only about 4 have benefitted the virus. The ‘Delta’ mutation is one of these.
Is ‘Delta Plus’ dangerous?
So far about 50 cases of ‘Delta Plus’ are detected in the samples analysed in India. In addition to India, around 200 ‘Delta Plus’ infections are found in several other countries worldwide including Britain, Canada, Japan, Poland, Portugal, Switzerland, Russia, and the US.
A mutation is classified as a ‘variant of interest’ and ‘variant of concern’ depending on its easy transmission, reduced neutralization by antibodies and vaccines effectiveness against the virus. Till now, the World Health Organization (WHO) has not classified ‘Delta Plus’ as a ‘variant of concern’ and experts believe there is not enough evidence to support the claims of this variant being a 'concern’ variant.
However, the Indian government is not taking a chance. Because of bitter experience of unpreparedness for the second wave, Indian government is treating ‘Delta Plus’ mutant as a variant of concern as a preventive step against another possible outburst of cases in the country.
INSACOG, a consortium of 28 laboratories of the Ministry of Health and Family Welfare, has said that the ‘Delta Plus’ variant has increased transmissibility, stronger binding to receptors of lung cells and potential reduction in monoclonal antibody response.
‘The Delta Plus variant is extremely transmissible, and even walking next to a Covid-19 patient who is a carrier of this variant without a mask may lead to the spread of infection’ AIIMs director Dr Randeep Guleria has said recently.
Fears are mounting that the Delta Plus variant could trigger a possible third wave of the Covid 19 pandemic in the country. The Delta variant contributed to the explosive second wave of the pandemic here, there is a possibility that the Delta Plus might explode in the third wave.
Is ‘Delta Plus’ susceptible to existing vaccines?
As on today, most of the experts hope that the available vaccines can also act against the variant. This is yet to be established. If it is so, it is well and good. If not, then what next?
The matter of concern is that the ‘Delta Plus’ variant has the capacity to overcome the monoclonal antibodies. This is known as ‘immune escape mechanism’. This is a boost to the ‘Delta Plus’ variant of Covid-19 virus. No other variants have this capacity.
Monoclonal antibodies are artificial antibodies that mimic the antibodies produced by the immune systems. They are produced through a process that involves extracting specific antibodies from human blood and then cloning them.
These monoclonal antibodies are designed to target the spike protein of Covid 19 virus. The monoclonal antibodies bind to specific parts of the spike protein, blocking its ability to infect healthy cells.
Most of the vaccines also are designed to produce antibodies against the spike proteins of the Covid-19 virus. If the ‘Delta Plus’ variant is capable to overcome monoclonal antibodies, will it be resistant to the antibodies produced by vaccines to spike proteins?
Union Health Secretary Rajesh Bhushan has stressed that both Covishield and Covaxin are effective against the Delta Plus variant. But to what extent and what is the proportion of antibodies produced by these vaccines will be effective against ‘Delta Plus’ is not yet known. We have no studies on this subject in India. However, some global experts are predicting that the effectiveness of the Covishield vaccine is only 60 percent at best against the Delta variant. Then, how much effective these vaccines to ‘Delta Plus’ variant? The answer is not known.
Even the World Health Organization has recently expressed concerns that the Delta variant of Covid-19 is reducing the efficacy of the existing Covid-19 vaccines in the world. Whereas the new Delta Plus variant contains a key mutation that allows it to evade immune responses, which means the effectiveness of vaccines against the new variant may be further lower. The effectiveness of the existing vaccines against ‘Delta Plus’ variant is only a hypothesis and not a study.
We can only hope that the existing vaccines will also act against ‘Delta Plus’ variant.
What can we do?
Moment the lockdown is relaxed, we experience ‘release phenomenon’. Many of us forget Covid appropriate behavior. The mask is not properly used or not used at all. We cannot avoid family, religious and social gatherings. Maintaining social distancing is a hard task. Most of us who have received one or both doses of vaccines also think that we are safe and have gained eternal immunity to Covid-19 virus.
And this is where we fail. We failed after the first wave and were badly hit in the second wave. Now the virus has gained further strength to infect and to cause serious illness. We are very close to the third wave. If our vaccine status does not protect us, we will be in danger because the virus is now stronger and might attack us with vengeance. The available vaccines are the only weapons we have to face the virus with, but at times the virus may become triumphant.
We have to be careful.
I repeat the words of Dr. Guleria, Director of AIIMS who said recently: ‘If cases have come down, let us not make the same mistake which we made after the first wave. We thought that the virus has gone and now we can do anything. We must understand the virus is still there and mutating. It is becoming more of a cause of concern’.
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