Delta variant vs. the vaccine rollout
Conversations with Data: #77
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Welcome to our latest Conversations with Data newsletter.
Confusion and uncertainty continue to grow over the numerous variants spreading across the world. To help us navigate the latest vaccine research and help explain how journalists can best cover this ever-complicated narrative, we invited vaccinologist Dr Melvin Sanicas back to the podcast.
In this episode, he covers everything from how the Delta and Delta plus variants differ to the pros and cons of mixing vaccines. He also explains how boosters work and why journalists should avoid using pre-prints in their reporting.
What we asked
Talk to us about the Delta variant and the Delta plus variant. How are they different?
Delta was designated as a variant of concern because of evidence of increased transmissibility. The increase in the reproduction number compared with the Alpha variant, which is the B117 is estimated to be around 55 percent. Given the increase in transmissibility, the Delta variant is expected to rapidly outcompete other variants and become the dominant variant over the coming months.
Delta plus is a sublineage of Delta. In India, researchers observed this K417N mutation, another kind of mutation on top of the mutations of Delta. So they called it Delta plus. While it has not yet been designated as a variant of concern by either the WHO or the CDC, Indian health authorities are closely monitoring this Delta plus variant because it's been reported in 11 countries, while the Delta variant has been reported in over 98 countries. It's not yet clear if this Delta plus carries additional risks or is associated with increased transmissibility like the Delta variant.
What new symptoms are associated with the Delta variant?
Researchers in the UK have reported a shift in symptoms that may be associated with the Delta variant. There's this application that's being used in the UK, called the Zoe App. People who have downloaded this application have reported symptoms like headaches, sore throat, runny nose and fever, similar to what people may experience with a bad cold. This is also similar to what doctors in the U.S. have encountered so far. More physicians are seeing more upper respiratory complaints such as congestion, runny nose and headaches, which were not very common in the previous versions of SARS-CoV-2. It's not yet clear why cold-like symptoms are increasingly being reported or if there is a link, if any, to the Delta variant. But this is something we are closely following.
Why do we see an increase in cases if certain countries in Europe have fully vaccinated half of their populations?
We tend to automatically think that this is because of the virus or the variant. But that's just one of the many reasons why cases are increasing. We should remember that this respiratory virus is spread mainly between people who are in close contact with each other or through aerosols or droplets in close spaces. An infected person needs to bring the variant to another person, and they don't do it on their own.
The countries seeing an increase in cases have moved out of restrictions even before they have fully vaccinated 50 per cent of their population. Because of social mixing and mobility, the number of gatherings has also increased. So we are expecting -- and we are now seeing an increase in cases. But what's important to remember is the fact that the number of hospitalisations and deaths are not increasing as much as the number of cases. That is showing us that the vaccines are actually effectively taming COVID-19. The vaccines remove COVID-19's ability to make people severely ill or put them in hospitals or kill them.
How much more severe is the Delta variant compared to the Alpha variant?
It is definitely more transmissible. We've seen a lot of data on that now. But in terms of the severity, more research is needed. But there are indications that the Delta variant may cause more severe disease. A study published in The Lancet in June looked at the impact of the Delta variant in Scotland, where it had become the dominant strain. They found out that the risk of hospitalisation from COVID-19 was roughly doubled for patients infected with Delta than people infected with the Alpha variant. Also, researchers in the UK are seeing similar trends in terms of the numbers of patients showing, as we've discussed earlier, different symptoms. So it might be the case, but I'm sure this is something that we will be seeing a clearer picture in the next few months.
Talk to us about the vaccine efficacy rates of the different vaccines.
This is the million-dollar question. The vaccines we have at the moment appear to offer good protection against the Delta variant. Most virologists and vaccinologists agree that fully vaccinated individuals likely face little risk with the Delta variant. Moderna, for example, announced last week that the vaccine is effective against the Delta variant.
Similarly, promising results have been found with both the Pfizer-BioNTech and the AstraZeneca vaccine. In fact, an analysis released in June by Public Health England (PHE) found that two doses of the Pfizer vaccine were 96 percent effective against hospitalisation from the Delta variant and two doses of the AstraZeneca vaccine were 92 percent effective. A previous analysis from the PHE also found that a single vaccine dose was less effective against symptomatic illness. The message here is that two doses are needed.
In Israel, where 57 percent of the population is fully vaccinated, a recent spike in COVID-19 cases was reported with the Delta variant, including infections amongst vaccinated individuals. But this did not mirror an increase in hospitalisations and deaths. As for Sinovac, the vaccine still offers protection. In the Guangdong province, where the first cases of the Delta variant were reported, none of those who were vaccinated developed severe symptoms. And all of those severe cases in Guangdong were from unvaccinated people. So that's also a good thing.
Sputnik V released a press release last week saying that the vaccine is 90 percent effective against the Delta variant. This is slightly lower than the reported vaccine efficacy against the original version of SARS-CoV-2. So that the high-level message is that vaccines work. Two doses work better than one, and the more people who get vaccinated, the better for everyone. Though, there's likely not much cause for worry amongst people who are fully vaccinated. Outbreaks can happen in places with low vaccination rates. And at the moment, most countries in the world have very low vaccination rates.
The UK plans to roll out boosters in September. Explain to us what boosters are and why they matter?
Vaccines protect us from dangerous pathogens, and once you have had your shot for a particular disease, you might think that you're always safe from it. But that's not necessarily the case. For some diseases, you need another shot to build strong immunity, and for others, your protection wears over time. Some viruses change or mutate like the flu over time, making your vaccine less effective. For most vaccinations, you need an extra dose of the vaccine known as a booster to help your immune system remember the pathogen. For COVID-19, we still do not know whether we need booster shots, but the elderly or the immunocompromised people may need boosters in the future.
What research is out there about mixing vaccine doses?
A study in Spain called Combivacs showed that vaccinating people with both the Oxford AstraZeneca and Pfizer/Biontech COVID-19 vaccines produce a potent immune response. A similar study in the UK called Com-Cov, analysed combinations of the same two vaccines. They found that people in the mix and match groups had higher immune responses and experienced higher rates of common vaccine-related side effects, such as fever if you compare these people to those who received two doses of the same vaccine.
Giving people first and second doses of different vaccines makes sense, but we do not know what will happen if people need a third dose to prolong immunity. Will it work as well? We are not sure. But this is already being done in many countries, including Germany. In fact, German Chancellor Angela Merkel took Moderna after receiving AstraZeneca as the first dose. This is now more accepted because we have some scientific data to show that this is OK.
What are the biggest blunders you are seeing with COVID-19 reporting in the media?
The one thing that I've seen a lot lately is the kind of reporting which says, "28 fully vaccinated doctors in Indonesia dead". However, the article fails to account for the denominator of say, 180,000. You don't protect everyone from Covid. We never said that Covid vaccines protect 100 percent of the population against infection.
And then, once a person is infected, there are other factors involved. Is this person healthy? Does this person have chronic medical conditions? Does this person have access to good health care? Or is this person a doctor in a small town where he has no choice but to work 72 hours straight? These things are not presented clearly. Or if they are presented, it is at the end of five paragraphs, and people don't read up to the fifth paragraph.
I saw another article saying, "Countries using Chinese vaccines continue to see Covid cases". These are a misrepresentation of what's happening. For example, you're saying that countries using Chinese Covid vaccines have cases, but you see Covid cases in the United States, in Israel and the UK that do not use Chinese vaccines.
What final piece of advice do you have for journalists?
I think, for the most part, journalists are keeping themselves up to date with whatever is out there in terms of new research on COVID-19. One thing that is important to remember not to report on preprints -- publications that have not been peer-reviewed yet. This is because pre-prints are useful, but they could change. Last year, many journalists were reporting preprints like they were a real peer-reviewed publication. At the moment, I don't see a lot of that, which is a good thing.
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Did you miss our live Conversations with Data Discord chat last week with Eva Constantaras and Anastasia Valeeva? Worry not -- the edited version will be out in our next issue. The pair discussed building a hypothesis for your data storytelling and the different training opportunities around the world for data journalists.
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