Laboratories are scrambling to create a safe and effective vaccine against Covid-19, a disease which has already caused more than one million deaths around the world.
The European Medicines Agency (EMA) is set to discuss progress authorising the use and distribution of two vaccines--one developed by pharmaceutical firm AstraZeneca and Oxford University and another in the works from drug companies Pfizer and BioNTech.
According to a survey by the Finnish Institute for Health and Welfare (THL) last spring, around 70 percent of respondents said they would take a vaccine if authorities recommended it. However, many still remember more than a decade ago the serious side effects of the H1N1 "swine flu" vaccine, Pandemrix, which was found to have multiplied the risk of narcolepsy, particularly among young people, a situation that damaged the public's confidence in vaccines as well as health authorities.
The director of the Vaccine Research Center at Tampere University, Mika Rämet, said the centre advises decision makers about new vaccines, but does not participate in policy-making. He noted that the centre is not currently conducting its own coronavirus vaccine study.
7 questions answered
Rämet answered seven questions about the possible efficacy and safety of a potential Covid-19 vaccine.
1. What is the difference between the two vaccines?
"Pfizer's is based on RNA technology. The coronavirus' genetic code is introduced into the body which produces a viral spike protein in human cells, eliciting an individual's immune response against part of the virus," Rämet said.
"The AstraZeneca vaccine is based on a [different] carrier virus, in this case an adenovirus which has been rendered non-divisible… The idea is that it will elicit a desired immune response [against coronavirus]," he explained.
2. Which one is better?
"I will not comment on that, but the good news is that there are two different options. If one doesn't work, then the other may well do," Rämet said.
3. What is known about their efficacy?
"Tens of thousands of people have already been vaccinated in trials, which means that both prompt immune responses. They look promising. In the coming weeks more accurate results will be available on how well they actually protect against the disease. We are eagerly awaiting [the results]," he said.
4. What are the demographics of the trial participants?
"At this stage the majority are working age, but Pfizer has extended the trials to 16-year-olds and at-risk populations with underlying illnesses as well as the elderly. When trials need to vaccinate tens of thousands of people to prove that they work, people of working age are the main group that most clearly show whether immune responses are developing. This kind of research can only be extended to specific groups, like children, [with special] discretion," Rämet explained.
5. What is known about the vaccines' safety?
"Results have already come in from second phase human trials, which usually have hundreds of test subjects. There were more than 1,000 subjects in the AstraZenca vaccine. It was found that nine-out-of-ten subjects developed the desired immune response with a single vaccine dose. There were no disadvantages of particular concern. The side effects were typical of vaccines, mainly redness and pain at the injection site, as well as a mild fever associated with the onset of a defence response," he said.
"Both vaccines are in the third phase of trials. The Pfizer study involved giving two doses to 25,000 people while the AstraZenca study gave one dose to 35,000. Authorisation to market the vaccines will only be made if the large-scale studies prove there is no serious harm in their use and their efficacy is adequate," Rämet said.
"In general, vaccines may be associated with side effects. The influenza vaccine, for example, is associated with a low increased risk of Guillain-Barré syndrome (a rare condition in which the immune system attacks a person's nerves). But it is also know that influenza infections are associated with an even higher risk of developing that syndrome than taking the vaccine. So, if you want to reduce the risk of getting the syndrome, you should take the influenza vaccine," he explained.
6. Can coronavirus vaccines create similar problems as the H1N1 vaccine?
"Narcolepsy has not been described in association with any vaccines other than Pandemrix. It was a very unfortunate and multifaceted side effect. It was probably a combination of certain genetic susceptibilities, the vaccine's antigens and the vaccine booster. It could also involve some unknown causes because the side effect was not seen in everyone," Rämet said.
7. Many healthy people of working age with Covid only experience mild symptoms. Is it still worthwhile taking the vaccine if it becomes available?
"The disease is typically tolerable in basically healthy people, even at the age of 49. But that age group has also been known to cause the need for intensive care as well as mortality," he said.
"The vaccine that will be introduced will have been tested on tens of thousands of people as well as received EMA approval. It will have been examined with a fine-tooth comb, which means that it will be possible to distribute it to specific groups of people. If a decision is made to do that, it means that the benefits for a particular group will outweigh the anticipated disadvantages--the risk of no vaccination are greater than being vaccinated," he said.
"Taking the vaccine is a voluntary decision, but avoiding the disease indefinitely is not a pleasant nor workable solution," Rämet said.