Science & Technology

How effective is the COVID vaccine against the Omicron variant?Epidemiologist explains

Understanding how much protection a vaccine provides is not as easy as it sounds.

Pandemiology has brought many tricky terms and ideas from epidemiology to everyone’s lives.Two particularly complex concepts are vaccines Effectiveness and effectiveness.. These are not the same thing. And over time, as new variants like Omicron emerge, they are changing too.Melissa Hawkins Epidemiologists and public health researchers At American University. She explains how well vaccines prevent illness, what affects these numbers, and how researchers calculate how Omicron is changing things.

1. What does the vaccine do?

A vaccination To activate Immune system that produces antibodies It remains in your body to fight exposure to the virus in the future. All three vaccines currently approved for use in the United States (Pfizer-BioNTech, Moderna, Johnson & Johnson vaccines) are available: Impressive success in clinical trials..

COVID vaccine injection

Clinical trials are used to calculate the effectiveness of a vaccine, but they do not necessarily represent the actual condition.

2. What is the difference between vaccine efficacy and efficacy?

All new vaccines require researchers to test vaccines against thousands of people and undergo clinical trials to see how well they work and are safe.

Effectiveness Is a measure of How well the vaccine works In clinical trials. Researchers design the study to include two groups, one receiving the vaccine and one receiving the placebo. They calculate the effectiveness of the vaccine by comparing the number of cases of illness that occur in each group of vaccination and placebo.

effectMeanwhile, I will explain how well vaccines work in the real world. It is calculated in the same way by comparing the illnesses of vaccinated and unvaccinated people.

Effectiveness and effectiveness are usually close to each other, but not necessarily the same. How the vaccine works is a little different from the test results after millions of people have been vaccinated.

Many factors affect how vaccines work in the real world. New varieties like Delta and Omicron may change things. The number and age of people enrolled in the trial is important. The health of the vaccinated person is also important.

Vaccine intake – Percentage of the vaccinated population – can also affect the effectiveness of the vaccine. When a sufficient proportion of the population is vaccinated, herd immunity begins to work.vaccination Even moderate or low potency can be very successful At the population level. Similarly, vaccines that are highly effective in clinical trials, such as the coronavirus vaccine, Low effect If the population does not have high vaccine intake, the impact is small.

The distinction between effectiveness and effectiveness is important. One is to explain the risk reduction achieved by the vaccine under test conditions, and the other is to explain how this changes in populations with different exposure and transmission levels. Researchers can calculate both, but they cannot design studies that measure both at the same time.

3. How do you calculate effectiveness and effectiveness?

both Pfizer When Modana They reported that their vaccine was more than 90% effective in symptomatic prophylaxis. COVID-19 (new coronavirus infection) infection. In other words, among those vaccinated in clinical trials, the risk of getting COVID-19 was reduced by 90% compared to those who were not vaccinated.

Imagine conducting a vaccine test. Randomize 1,000 people to be vaccinated in one group. Random another 1,000 to be given another group of placebos. 2.5% of people in the vaccinated group are infected with COVID-19, while 50% of people in the unvaccinated group are infected with COVID-19. This means that the vaccine is 95% effective. (50% – 2.5%) / 50% =. Judge that it is 95. Therefore, 95% indicate that the proportion of illness in the vaccinated group has decreased. However, a 95% effective vaccine does not mean that 5% of vaccinated people will be infected with COVID-19. Even better news. The risk of illness is reduced by 95%.

Vaccine efficacy is calculated in exactly the same way, Observational study..Early on, the vaccine was pretty much over 90% valid By preventing serious illnesses in the real world. However, due to its nature The virus changes, This may change the effect.For example, according to one study, by August 2021, when the delta was skyrocketing, the Pfizer vaccine was 53% effective in preventing serious illnesses in nursing home residents In this case, age, health problems, weakened immunity, and new strains all reduced efficacy.

Coronavirus SARS-CoV-2 Aomic model

All new variants of coronavirus are slightly different from the original strain on which the vaccine was based, so immunity to the variants may be different. Credits: Alexey Solodovnikov, Valeria Arkhipova / WikimediaCommons, CC BY-SA

4. What about Omicron variants?

Preliminary data on Omicron and vaccines coming soon Vaccines have been shown to be less effective.Best estimates suggest that vaccines are around 30% -40% effective in preventing infection When 70% effective in preventing severe illness..

A Preprint survey – What has not yet been formally reviewed by other scientists – What was done in Germany found that antibodies in the blood collected from people who were fully vaccinated with Moderna and Pfizer showed. Decreased neutralization effect of Omicron mutants..Other small preprints Studies in South Africa When England It showed a significant reduction in how well the antibody targeted the Omicron mutant.more Expected breakthrough infectionCompared to other variants, the immune system’s ability to recognize omicrons is reduced.

Three COVID-19 vaccine doses

Currently, most people in the United States are eligible for a booster coronavirus vaccine that may help protect them from Omicron variants.

5. Do boosters boost immunity to Omicron?

Initial data reinforces it The third dose helps boost Immune response and protection against Omicron, 70% -75% effectiveness..

Pfizer reported People who have been vaccinated twice are more susceptible to infections from Omicron, Third shot improves antibody activity against the virus.. It is based on laboratory experiments with the blood of vaccinated people.

Booster doses can increase the amount of antibody and the ability of the person’s immune system to protect against Omicron. However, unlike the United States, The world has no access For booster dose.

6. What does this mean?

Despite the reduced effectiveness of the vaccine against Omicron, the vaccine works and Maximum public health outcomes.. Vaccines have varying levels of efficacy and are still useful.Influenza vaccine is usually 40% -60% effective Prevents millions of illnesses and more than 100,000 hospitalizations in the United States Every year..

Finally, the vaccine protects not only those who have been vaccinated, but also those who have not been vaccinated.Those who have been vaccinated Unlikely to spread COVID-19 reduces new infections and protects society as a whole.

Written by Melissa Hawkins, Professor of Public Health, American University.

This article was first published conversation..conversation

How effective is the COVID vaccine against the Omicron variant?Epidemiologist explains How effective is the COVID vaccine against the Omicron variant?Epidemiologist explains

Back to top button