4 kinds of mutant strains, how can your vaccine adapt to the ever-changing situation? How to coexist with the virus in the new crown?

In recent days, new cases have appeared in Xiamen, Fujian, and Heilongjiang. Among them, 56 positive cases in Fujian were Delta variants. Since the virus replicates the genetic genome during transmission, due to unavoidable replication errors, the viral genome changes and thus produces mutant strains, which brings new challenges to epidemic prevention. However, not all mutations will bring huge risks. Only some mutations will change the characteristics of the virus, making the virus more contagious and toxic. Which mutant strains are worth paying attention to? What is their infectious ability? How far is it spread? Do existing vaccines have a protective effect against them?

Image source: Global Times

Virus mutation

Currently, the four mutant strains that pose the greatest threat to the world include: Alpha, Beta, Gamma and Delta.

1. Alpha

It spread rapidly at the end of 2020 and became the mainstream variant in the first half of 2021. In November 2020, the Alpha variant was first detected in a sample in Kent, England in September. Alpha is particularly contagious. At the same time, cases infected with Alpha react more strongly, with patients coughing constantly and mucus containing the virus flowing out of their mouths and noses - which also makes the virus more contagious.

AstraZeneca and Sinovac vaccines are both effective against Alpha. According to a report on the Pharmacy Times website on July 7, the Canadian Institute for Immunization Research found that the AstraZeneca vaccine is 90% effective against Alpha; according to the Thaiger news website on June 29, the Thai public health department found that two doses of Sinovac vaccine are 71% to 91% effective against Alpha.

2. Beta

It is highly contagious and has a very strong immune escape ability. Beta was first discovered in samples from South Africa in May 2020, and soon became the most widely spread virus variant in South Africa. Currently, Beta-related cases have been found in 130 countries around the world. Beta is highly contagious and good at evading tracking by the human immune system. Beta is about 50% more contagious than the original new coronavirus, and has a higher hospitalization rate, ICU occupancy rate and risk of death. Pfizer's vaccine has a good resistance to Beta. According to the BBC, research data from Pfizer's vaccine in Qatar showed that its effectiveness against Beta was 97%, especially for severe cases.

3. Gamma

The Gamma variant is the biggest threat to the epidemic in South America. It was first discovered in samples from Brazil in November 2020. In June 2021, it accounted for 76% of the new crown cases in South America. It is the most important new coronavirus strain in the South American epidemic and has spread to 75 countries including the United States, the United Kingdom, and Russia. The Gamma variant is highly infectious and may increase its transmissibility by 1.4 to 2.2 times and may cause reinfection. However, the vaccine is still highly effective against Gamma.

4. Delta

Of course, everyone is particularly concerned about the mutant strain (Delta strain) prevalent in India. The SARS-CoV-2 B.1.617.2 (Delta) variant was first discovered in Maharashtra, India at the end of 2020 and has spread throughout India. Its prevalence rate is much faster than the previously existing B.1.617.1 (Kappa) and B.1.1.7 (Alpha) lineages, and it has now spread to more than 90 countries around the world. The Delta strain has not only caused the rapid spread of local cases in Guangzhou, China, but has also landed in the UK since March this year and has been detected.

On July 5, a medical staff member worked at a new coronavirus testing station in Herrsching, Germany.

Xinhua News Agency/AFP

According to the Global Initiative on Sharing Influenza Data (GISAID), as of July 26, Delta accounted for 84% of infections in Asia, 97% of infections in the UK, and 80% of infections worldwide. The World Health Organization and the European Center for Disease Prevention and Control jointly released an epidemic report on the 23rd, saying that based on current trends, the Delta strain will become the world's most dominant new coronavirus variant in the coming months, and unless a more competitive strain emerges, the Delta strain will continue to spread and replace other variants. Delta is more contagious than any previous new coronavirus variant, but there is no detailed data to show whether it will cause more serious illness.

Delta is 50% more contagious than Alpha and twice as contagious as the original coronavirus. Why is the Delta virus strain so contagious? Recently, Professor Ravi Gupta of Cambridge University and his research team discovered that Delta coronavirus can cause super strong transmission by evading neutralizing antibodies and increasing replication ability. Their research results were published in the internationally renowned journal Nature on September 6, 2021.

In an analysis of more than 130 health care workers who were infected with COVID-19 after vaccination at three centers in India, the study observed that the AstraZeneca vaccine had reduced effectiveness against B.1.617.2 relative to non-B.1.617.2 viruses, reaffirming previous in vitro findings that SARS-CoV-2 B.1.617.2 (Delta) has reduced sensitivity to neutralizing antibodies and increased replication fitness, resulting in immune evasion and higher infectivity of the virus. Therefore, the reduced vaccine efficacy against the highly evolved and immune-evading B.1.617.2 (Delta) variant is another reminder that strict infection control measures need to continue in the post-vaccination era.

How can vaccines adapt to ever-changing situations?

Image source: Xinhuanet

The biggest achievement in the global fight against the pandemic is the launch of COVID-19 vaccines at the end of 2020, including inactivated vaccines and recombinant subunit vaccines prepared using existing technologies, as well as mRNA vaccines and adenovirus vector vaccines used for the first time. Vaccines are an important means of controlling the pandemic, and the successful development of multiple vaccines within a year of the outbreak is a remarkable achievement.

The "Spring Vaccine Operation" vaccination site photographed in Port Moresby, the capital of Papua New Guinea on June 28, 2021

Image source: WeChat public account "Global Magazine"

However, having a vaccine does not mean that the epidemic can be controlled. The first key point is to give more than 70% of the world's population one or more shots in their arms. In human history, this has never been done in a few years. As of September 14, the proportion of the world's population that has completed vaccination has just exceeded 30%, which is still far from the 70% target. There are less than 20 countries with a vaccination rate of more than 70%.

In less than 10 months, more than 2.3 billion people were vaccinated, which is an unprecedented speed, but it is still too slow to control the new crown epidemic. The lack of sufficient herd immunity is one of the reasons why the Delta strain triggered this wave of epidemic.

Large-scale vaccination has created evolutionary pressure on the new coronavirus. Because the vaccination rate is not fast enough, the virus has sufficient time to mutate, resulting in the continuous emergence of new variants that have the ability to escape immunity. In the near future, variants that can escape vaccines may appear.

Another key point in controlling the COVID-19 pandemic with vaccines is the ability to cope with virus mutations. Compared with the ever-changing virus, vaccines are currently in a constant state. The previous new generation of vaccines targeted Beta and have not yet been launched. Delta has become the main epidemic strain, and vaccines administered worldwide are still targeted at the original strain, with varying degrees of decline in their ability to prevent Delta. Whether in terms of vaccination scale or in terms of replacement, vaccines are more than one step behind the virus.

Fortunately, however, vaccinated people can indirectly protect those around them who are not vaccinated, especially the elderly and children with low vaccination rates. Research from the Israel Institute of Technology has confirmed that vaccination can effectively protect unvaccinated people. After monitoring 177 communities and analyzing the incidence of COVID-19 infection in all unvaccinated people under the age of 16, for every 20% of the population vaccinated, the positive test rate of the unvaccinated population will drop by 2 times. These data tell us that effective vaccination can not only improve individual resistance to the virus, but also help improve the resistance of the entire population to the virus and significantly slow the spread of the virus.

At present, only by completing the widespread vaccination can we establish a barrier to the spread of the virus. Once the virus is introduced, even if it is a mutated virus, its transmission speed will be greatly reduced. At this time, we can calmly take precise prevention and control measures to greatly reduce the hazard level of the virus and maintain the normal openness and operation of the world.

The epidemic and us

The COVID-19 pandemic will definitely continue for some time, but there is no accurate estimate of how long it will last. Some experts believe that if vaccination is continued, the epidemic is expected to be under control in 2022, while others predict that more aggressive variants will appear in 2022 and the epidemic will last longer. This is a difficult problem for governments of all countries. Among the countries that are currently capable of epidemic prevention, a few have adopted a zero-COVID strategy, a few have adopted a flat-line strategy, and most have taken a middle route.

More and more countries are lying flat, but this is based on the premise of full opening after the vaccination rate reaches 70-80%. Most countries are taking control measures to varying degrees, which means that the lives of most people in the world are still affected by the epidemic. What kind of epidemic prevention strategy to adopt depends on many factors such as national conditions, social form and the degree of public recognition. They are not comparable to each other. The strategy that suits the situation of the country is the best strategy. For ordinary people, what they should consider is not this, but how to get through this disaster in the safest way.

First, get vaccinated. Regardless of the vaccine, its effectiveness in preventing infection is affected by virus mutations, but it still has a very high effectiveness in preventing severe illness and death, so vaccination is undoubtedly the first choice.

Secondly, try to eliminate your own risk factors as much as possible. Not everyone is equal in the face of COVID-19. The elderly and those with underlying diseases are at a much higher risk of severe illness and death than other groups. Aging is unavoidable, and underlying diseases cannot be cured, but can be well controlled, so it is necessary to more actively control relevant indicators and symptoms.

Among various risk factors, obesity is the number one risk and it is also a risk that can be reversed. This risk factor can be completely eliminated by losing weight. Therefore, overweight people must work hard to reduce their weight to a normal level and control the strain.

Diabetes and high blood pressure are two other major risks, but if blood sugar and blood pressure are under control, you are not considered a high-risk group. You need to keep blood sugar and blood pressure within the normal range by improving your lifestyle and taking medication.

Heart disease is also a major risk factor. You need to control your blood lipids and blood pressure, eat a healthy diet, and exercise more to reduce the risk of cardiovascular disease.

Image source: CCTV News

Finally, adjust your mental state. During the epidemic, the world is anxious, and many people have even reached the point of depression. You should regularly adjust your mentality and take various measures to relax yourself in order to cope with the huge pressure brought by the epidemic. The epidemic will eventually pass, so don't let this epidemic scar your body and mind.