SL Long Way From Achieving Herd Immunity -- Prof. Neelika Malavige
By Methmalie Dissanayake and Aruni Mallawarachchi
Sri Lanka has a long way to go before achieving herd immunity naturally (through infection) or artificially through vaccination against COVID-19, said Prof. Neelika Malavige, Head of the Department of Immunology and Molecular Sciences of the Sri Jayewardenepura University.
In an interview with Ceylon Today, Prof. Malavige further said epidemiologists have provided evidence that Sri Lanka has community transmission at the moment.
Prof. Malavige focuses on investigating the mediators that cause vascular leak in dengue and immune correlates of protection against severe dengue. She has now also focused her work on the immunopathogenesis of COVID-19, correlates of protection, and virus strains.
Following are excerpts of the interview:
Q: What is your opinion on the current COVID-19 situation in the country?
It is clear the current situation is very bad. This is my personal view.
Q: Why do you think so?
During the past few days, about 2,000 to 2,500 patients were reported daily. This is not the real number and we all know that because all the patients in the county cannot be detected. This is why I said the current situation is very bad. But this is not the worst situation. We have to understand that too.
Q: Do you mean the situation can escalate?
What we are scared of most is COVID pneumonia and deaths that occur due to that. We do not care much if we show symptoms like cold and not any another symptom after that. Now, many are scared of the situation in India, because in our country we can see a spike in the number of patients who develop pneumonia. We can also see a surge in ICU admissions.
Extreme COVID-19 symptoms are normally shown after the end of the second week of being infected with the virus.
It means, a person dies of COVID-19 after two to three weeks of being infected with the virus. So, the current COVID-19 deaths and ICU admissions are as a result of what occurred two to three weeks ago. The results of the current situation you and I are talking about, can be seen in another two to three weeks.
Q: You mentioned that the number of patients which is reported these days is not the real number. Do you mean the data is inaccurate?
I cannot comment about the data available because I am a university academic, not an official at the Health Ministry. So, I don’t have such data. I don’t know more about data than you.
What I meant was we cannot detect all the patients in the country at this moment from tests. Now, about 2,000 patients are reported daily from the tests. But there are more who haven’t undergone testing. This is what I’m saying. We assume there are more patients in the country than the number of patients reported. This is dangerous.
Q: Do you mean there are many asymptomatic patients?
Yes. This is the most dangerous situation. Compared to the other countries, there are more persons here who are asymptomatic. They don’t show any symptoms. But they spread the virus. During the first and second waves, we quarantined those who were asymptomatic to avoid spreading the virus. Even now, there are many who are infected but they don’t show symptoms.
When someone displays any kind of COVID-19 symptoms, we tend to be careful. But when someone doesn’t display symptoms, we don’t care much about it.
Q: It is said this virus is active in the air for some time. In such a situation, how can we protect ourselves?
Many interpret this fact in a wrong way. This virus does not spread through places with a huge space or places like beaches, because the atmosphere in these places is wide. When there is good ventilation, spread of the virus remains very low or is unlikely. Viruses spread indoors. For example, the virus can be spread in an enclosed space where there is a large crowd. The virus could remain in such places for a few hours and then someone can contract it.
It is not like when your neighbours are infected, the virus is airborne and infects you.
Q: Can the virus be destroyed by disinfecting suspected places, like offices and shops?
Nothing significant will happen when spraying chemicals in such places using large tanks. I don't see the point of doing that. COVID-19 doesn’t spread through droplets or viruses on the floor or anywhere. Therefore, disinfecting floors, chairs, tables, and drainage systems is futile. COVID-19 doesn’t spread like that. You can’t catch the virus even if there are five patients in the neighbour’s home.
We need to sanitise frequently touched surfaces like doorhandles and handrails of stairways. There is no point in cleaning floors, drainage systems, and walls.
Q. What is the maximum daily capacity of conducting PCR tests in Sri Lanka at the moment?
Currently, I believe we do around 25,000 per day. Most laboratories have exceeded their capacity and are trying to clear backlogs.
Q. What is the ideal positive test ratio to confirm that we are doing adequate testing?
Currently our test positivity is 7 per cent during the last few days, with the positivity rates being slightly higher. This means that we are unlikely to be detecting all cases and we need to increase the testing capacity. However, the number of tests a country can do cannot be increased suddenly. Any country has a limitation in the maximum number of tests it can do. What I believe is that since the positivity rates are very high, which obviously indicates a very high transmission, we should take all necessary steps to reduce the number of cases. Also, to change our testing strategy based on the change is the immediate goal. Currently, I think it’s important to identify every symptomatic COVID-19 individual, as they would require hospital treatment.
- The percentage of all coronavirus tests performed that show someone has COVID-19. If the per cent positive was more than 50 per cent in an area, doctors would have to do only two tests to find one case. If an area's per cent positivity rate is below 1 per cent, you would have to do over 100 tests to find one case.
Q: It is said the British variant spreads faster than other variants. What is so unique about it?
That is an important question. Currently, across the world, several COVID-19 variants have been identified. These variants do not significantly differ from each other. However, the WHO has identified four variants which it sees as stronger than others.
To class these variants as more powerful than other variants, these variants should possess certain qualities. First, it should spread quickly. Second, it should cause more people to fall sick and more deaths than other variants. Third, the protection granted by vaccines must be diminished. Fourthly, there must be an increased likelihood of repeated infections.
If these qualities are present in a variant, then the WHO will classify the variant as more powerful than common variants. The WHO has identified four such strains and one of them is the British variant. The other three variants are the South African, Brazilian and Indian variants.
Q: Is there a risk of the Indian variant spreading in our country currently?
This strain has been identified in a quarantine centre, from a person who had arrived from overseas, not from the society.
Q: Your team released a warning on 8 April regarding the British variant?
No, many people have reported that incorrectly. When conducting PCR tests, the British variant and two other variants show certain differences. Our team identified these differences. At the time, we stated that there are certain differences and a new variant could have entered the country.
Without conducting generic tests, it is not possible to identify the new variant. On 8 April, we said there was a new variant in Sri Lanka, but we did not say that it was the British variant. On 23 April, during a Media briefing, I said that there is a new variant but don’t know if that was the British variant.
Q: International experts say this virus is rapidly evolving. What does that mean?
Yes, that is the nature of the virus. Any virus will evolve and that is how the four new variants identified by the WHO appeared. A new variant could surface in Sri Lanka too.
However, the COVID-19 virus mutates more than most other viruses.
That is what has led to these new variants and in the future there will be more. We know that during the 1918-1919 period, that around 50 million people died of influenza. This is more than those who died in both World Wars.
From this incident, we can predict the level of destruction that could be caused by viruses. We should not forget that.
Q: Due to these several mutations, can we be certain the vaccines will continue to be effective?
Compared to 1918 and 1919, the world’s technological capacity has greatly improved. To make vaccines is not a difficult endeavour and already there are several effective vaccines that have been manufactured.
Therefore, it is safe to place your faith in vaccines. Many diseases, such as smallpox and measles, have been eradicated due to vaccination programmes. There are already several effective vaccines which have received WHO approval. Pfizer, Moderna, Oxford-AstraZeneca, Russia’s Sputnik V and China’s Sinopharm are vaccines that have been tested and shown to be successful.
Q: Can these vaccines provide protection against the British variant?
According to international research, these vaccines are effective against the British variant. There are doubts only about the South African variant.
Q. Does Sri Lanka conduct serosurveillance? If not, what are the reasons?
Yes, we do. Our Department of Immunology and Molecular Medicine did one at the CMC, in January 2021, because that’s where the highest number of cases were detected. Serosurveillance is important to identify the true extent of the outbreak and to plan for the future. The results of our survey will be released soon.
Vaccination provides immunity. There is no need to conduct serosurveillance on those who have received the vaccine. However, we are conducting several studies to find out the immune responses to the different vaccines.
- Serosurveillance provides estimates of antibody levels against infectious diseases and is considered the gold standard for measuring population immunity due to past infection or vaccination.
Q. How can we confirm whether there is a community spread of COVID-19 in Sri Lanka? Can a community spread be detected by conducting random screening?
Community spread is when there are individuals who become positive, with no known contact. I think it is very obvious it is happening now. I am not an epidemiologist, but all my epidemiology colleagues have provided evidence that we have community transmission now.
Q. Has a study been conducted on the herd immunity level in Sri Lanka at the moment?
Herd immunity is when there is sufficient immunity in the community that stops transmission of an infection. This can be achieved naturally (through infection) or artificially through vaccination. In the CMC, where there were a lot of cases from November to January, the infected proportion was very much below herd immunity. Therefore, Sri Lanka has a long way to go to achieve herd immunity by whatever method mentioned above.
Q. There is a shortage of Oxford-AstraZeneca Covishield vaccines for about 600,000 people who received the first jab in Sri Lanka. What will happen to them if they don't receive the second jab after the recommended time period?
If they don’t get it at exactly 12 weeks there is no issue. In reality, when we look at other vaccines, people very rarely get vaccines on the exact date. Therefore, a delay of 2 to 3 weeks is not a cause for concern. However, any further delay will result in a gradual drop in immunity to the virus. How fast it will fall and how much we don’t know. But we know that at 4 to 12 weeks the antibody responses remain more or less the same.
Q. Can those who didn't receive the second dose of the AstraZeneca jab be given a dose from another brand? If yes, in how many weeks should the other brand be administered?
If the second dose of a different vaccine such as Pfizer can be administered within the given time period, then there is no need to restart the whole vaccine course. In Europe, some individuals who received AstraZeneca as the first dose are in fact receiving Pfizer as the second dose. Several trials are ongoing about mixing and matching vaccines and hopefully we should be getting data soon.
Q. Can AstraZeneca be combined with the Sputnik V vaccine?
We don’t have data and clinical trials are in progress. Sputnik V is also a vaccine developed on an adenoviral vector platform like AstraZeneca. Therefore, theoretically there shouldn’t be a problem. But it is good to have data.
Q. Are there plans to get down the Sputnik V Light single jab?
That would be a good idea. If it is available, I believe the authorities will get it.
Q. When will the people who received the first dose of the Sinopharm vaccine receive the second dose?
In 4 weeks.
Q. There are plans to bring down the Pfizer-BioNTech vaccine as well. If so, how much time will it take to prepare storage facilities?
We already have storage facilities. Also, the vaccine can be kept in the cold storage pack which it comes in and stored at room temperature for 10 days.
Q. Is there a comparative survey on vaccines in Sri Lanka? Do we have any research about that?
Yes. We are currently doing that. We have done detailed studies on the AstraZeneca jab and we have submitted the data for publication. The data is freely available as a preprint for anyone to access it.
- Comparative survey research refers to any survey research that is developed to compare certain groups.
Q. According to some projections, Sri Lanka is at a critical stage. What do you think about these models?
These models have shown to be very accurate in many other countries. So, we need to take these seriously.
Q. These days, many COVID-19 patients are being detected from rural areas. We didn't see this situation in both the first and second waves. What should we do in a situation like this?
Preparing for a high number of patients by building hospitals and beds and improving ICU facilities is highly commendable. However, it is difficult to increase human resources and other facilities. Although vaccines are the long-term solution to end the pandemic, they will take some time to work, and to immunise sufficient numbers (70-80 per cent) it will take a long time. Therefore, it is very important to reduce the number of cases, by methods we have been practicing all along.