AstraZeneca Vaccine Q&A with Professor Park Wan-beom of Seoul National University Hospital

Corona 19 vaccination began on the 26th of last month. The vaccine administered for the first time in Korea was AstraZeneca, and there is controversy over efficacy and safety. With the help of Professor Park Wan-beom of the Department of Infectious Diseases at Seoul National University Hospital, we answer questions about the AstraZeneca vaccine through Q&A.

-How is the AstraZeneca vaccine different from the Pfizer vaccine?

△ What the two vaccines have in common is that they both use state-of-the-art technology to temporarily make some proteins of the coronavirus in our bodies. As a result, we are not infected with the virus, but our body becomes immune to the virus as if the virus entered the body. However, while Pfizer vaccine uses a genetic material called RNA to make a viral protein, the AstraZeneca vaccine uses an adenovirus to deliver a genetic material called DNA. Adenovirus, which carries DNA in the AstraZeneca vaccine, is relatively safe because it does not have the ability to proliferate and does not intervene in our body’s DNA. Basically, both vaccines make our body produce the protein of the coronavirus, but the types of genetic material they administer are different.

-It is known that the vaccine efficacy is 60~70% after vaccination with AstraZeneca. What does it mean?

△Vaccine efficacy refers to how much the vaccine can reduce patients compared to when the vaccine was not administered. In other words, the vaccine efficacy of 70% means that if there are 10 patients when they do not get the vaccine, it can be reduced to 3 when they get the vaccine. If the vaccine’s efficacy is 90%, the number of patients can be reduced from 10 to 1 through the vaccine.

-Recently, the government has recommended that elderly people over 65 years of age carefully prescribe injections according to the judgment of medical personnel. In what ways do you need attention?

△ The clinical trial of the AstraZeneca vaccine did not include many elderly people over 65 years of age. However, it is expected that it will be able to reduce corona patients by confirming that antibodies at a level similar to those of young people in the elderly are formed. As we are waiting for the results of clinical trials for senior citizens, we recommend that you administer them carefully.

-Are there any additional guidelines regarding vaccination for adolescents under the age of 18 and infants?

△ Children and adolescents are not included in the priority vaccination group because they have a lower risk of developing COVID-19 compared to adults and are less likely to progress to severe disease. In addition, there are no studies that have systematically evaluated the corona19 vaccine for children and adolescents, so there are no corona vaccines approved for under 16 years of age worldwide. In the future, it is expected that the vaccination and target will be decided after the prevention effect and safety evidence for COVID-19 in children and adolescents is secured.

-There is public opinion concerned about the side effects of the AstraZeneca vaccine. What are the known side effects of overseas cases and are they worrisome?

△ During the clinical trials of the AstraZeneca vaccine, there were a few rare cases of transverse myelitis, which raised concerns about side effects. However, it was confirmed that it was not related to the vaccine. The AstraZeneca vaccine also has side effects similar to other vaccines. The injection site may have pain for about 3 days, and fever, chills, fatigue, headache, and muscle pain may be present for about a day or two. The difference from the Pfizer vaccine is that the Pfizer vaccine has more severe side effects at the second dose than the first dose, whereas the AstraZeneca vaccine has milder side effects at the second dose than the first dose.

-Is it possible to cross vaccination with other vaccines (AstraZeneca for the first, Pfizer for the second)? (In Israel, it is said that there was an incident in which an individual was vaccinated five times due to excessive worries.)

△ Cross-vaccination with other vaccines is not recommended because the safety or effectiveness of the vaccine has not been confirmed. That is, two doses should be given with the same vaccine.

-Why is the social concern about the AstraZeneca vaccine somewhat higher than that of Pfizer et al.?

△ In the case of Pfizer vaccine, large-scale clinical trials of more than 40,000 people were systematically performed well under a single protocol. On the other hand, the AstraZeneca vaccine grouped four clinical trials, each slightly different, and announced the interim results in December of last year. There were fewer elderly people, the interval between the two administrations was different, and there was an unintentionally small dose of the group. As a result, there were concerns that the efficacy of the vaccine was jagged and inconsistent. However, as research continues and the results of follow-up studies come out, concerns about the AstraZeneca vaccine have been resolved to some extent. Researchers recently announced that the longer the interval between doses of the two-shot vaccines, the better the effect. When administered at 12-week intervals rather than 6-week intervals, the vaccine effect increased by 82%. There were also concerns that the AstraZeneca vaccine could not prevent asymptomatic infection and transmission, but a recent study found that vaccinating the vaccine would reduce the amount of virus excretion and duration even if infected. These results suggest that AstraZeneca vaccine may not only reduce the incidence of patients, but also block the spread of infection.

-Why is Pfizer vaccine and AstraZeneca vaccine different?

△ Pfizer vaccine and AstraZeneca vaccine have no different indications for vaccination. Since the supply of vaccine is insufficient, the advantages and disadvantages and characteristics of the vaccine are being considered in the process of selecting an inoculation target. Pfizer vaccine is effective, but storage and administration locations are limited because it must be stored at an extremely low temperature of -70 degrees Celsius. AstraZeneca vaccine is a little less effective and data on the elderly are insufficient, but it can be stored at normal refrigerated temperatures. In consideration of these characteristics and strengths and weaknesses, inoculation hospitals and targets are selected.

-How much is the immune effect of each of the COVID-19 vaccines?

△ Pfizer vaccine efficacy was 95%, showing very good results, and a new technology called RNA vaccine opened a new paradigm in the vaccine field. In the case of the AstraZeneca vaccine, the vaccine efficacy was 70% in the interim results last year, but a recent study reported that the efficacy could be increased to 82% when the vaccine administration interval was increased to 3 months. Considering that the flu vaccine efficiency is around 50%, both vaccines are excellent vaccines in terms of effectiveness. However, the AstraZeneca vaccine needs to wait a little longer for the results of clinical trials targeting the elderly.

-Is it okay for pregnant women or cancer patients to get the vaccine?

△If pregnant women are infected with COVID-19, the risk of complications increases somewhat, but data on vaccine safety in pregnant women are still lacking. However, if you are at high risk of exposure to the virus or have other underlying diseases such as diabetes or obesity, you need to consult with your doctor about vaccination. Cancer patients are also highly likely to progress to severe disease if they become infected with Corona 19, but data on the effectiveness and safety of vaccination are also insufficient. Since the current vaccine is not a live virus, side effects are not of great concern. Rather, there is a possibility that a sufficient immune response may not be induced when the vaccine is given in a state of reduced immunity. Therefore, patients undergoing chemotherapy should not be relieved even if they are vaccinated and should strictly follow personal hygiene such as masks. It is also recommended to be vaccinated by carers and family members caring for cancer patients.

-Can I get Corona 19 even if I get vaccination?

△ Up to one week after the second vaccination of the vaccine, the formation of immunity is incomplete, and you can get Corona 19. Since the vaccine efficacy is not 100% even one week after the second dose of diarrhea, symptoms or asymptomatic infection may occur due to COVID-19. However, if you become infected after vaccination, your symptoms are milder and less likely to progress to severe symptoms compared to when you did not get the vaccine, and because of less virus excretion, the risk of infecting others is reduced.

-Wouldn’t the AstraZeneca vaccine not be effective against a variant coronavirus such as a mutant virus from South Africa?

△ When a virus strain occurs, the efficacy of a specific vaccine may decrease depending on the degree of mutation. AstraZeneca vaccine was reported to be less effective in preventing mild infections caused by mutant viruses from South Africa. Fortunately, according to a recently published study, the efficacy against the UK mutant virus was maintained at 74.6%, similar to that of other viruses.

-Should the Corona 19 vaccine be vaccinated every year like the flu?

△ It is difficult to know the answer at this time. It will depend on the duration of immunity obtained from the vaccine, the outbreak and prevalence of the mutant virus, and the degree of mutation. However, the coronavirus does not mutate as fast as the flu virus. And, considering that the acquired immunity will last 2-3 years in the light of previous SARS virus experiences, I think the chances of getting a corona vaccine every year like the flu are low.

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