Covid 19 Coronavirus: What You Need to Know About Vaccines and Herd Immunity

Sounds simple. We have released the Covid-19 vaccine to the public and have enough immunity to stop the coronavirus, causing further outbreaks.But as a vaccine expert at the University of Auckland Dr. Helen Petsis-Harris And Dr. Janine Painter tell me Jamie Morton, Herd immunity is not always easy.

We have heard a lot about “herd immunity” and when and how to reach it in the development of vaccination. What is Herd Immunity Really?

Dr. Janine Painter (JP): That is when there are a sufficient number of people in a population that is less susceptible to disease or that the diseased organisms cannot replicate well, and unvaccinated people are at no risk or are very low.

Dr. Helen Petsis Harris (HPH): It is truly “community immunity” and protects enough people to stop the chain of infections.

The number of people who need immunity to create this community immunity depends on the disease, including the infectivity and spread of the disease.

So which virus did you actually achieve herd immunity?

JP: JP: There are smallpox, rubella, mumps, human papillomavirus (HPV), and rotavirus.

HPV vaccination was a great example of herd immunity protection, as the campaign initially included only vaccination of girls.

However, when the HPV infection rate in girls exceeded 50%, genital warts in unvaccinated boys decreased. The vaccinated girls were actually protecting the boys.

What kind of illness do you have? The 2019 outbreak has shown that we are still vulnerable to measles.

HPH: Another example of an immune elusive disease in the community at this time is whooping cough.

Even if you haven’t experienced the illness, you can prevent it from happening again for the rest of your life.

Like tetanus, it does not spread from person to person, but there are also diseases that are lurking in the environment, such as soil.

What we always need to be vaccinated.

In general, what are some of the major misconceptions about this concept? And what are the variables that lower or raise the herd immunity threshold, such as the well-discussed “R” value and basic reproduction number?

JP: JP: One is that herd immunity can be achieved by natural infection.

If the virus infects everyone and immunizes them, but some people get sick or die in the process, this is not “herd immunity” because the unimmunized people are not protected. ..

It is survival of the fittest.

The other is that there is a “fixed goal” that can be stopped or delayed when the vaccination effort is reached.

It’s all based primarily on “R-values”. This is the average number of other cases created by one infected person.

HPH: Indeed, if herd immunity from natural infections is actually achievable, then there is measles.

In the absence of the vaccine, almost everyone gets measles, and those who survive are generally immune for life.

However, measles epidemics continue to occur without vaccines, so community immunity to measles can only be achieved by using measles.

last week, Interesting study at the University of Sydney Australia has suggested that herd immunity can be reached with a 70% vaccination rate using only the Pfizer-BioNTech vaccine that New Zealanders receive this year. We also found that Australia’s current “hybrid” program (using shots of less effective AstraZeneca as well as the Pfizer vaccine) does not achieve herd immunity at a high vaccination rate of 90%. It was. What can we do from such research? And do they mean anything to New Zealand?

JP: JP: As the Australian-New Zealand border begins to relax, it will have the greatest impact.

In the meantime, it may serve as a guide on when and how to start easing border control.

If you’re struggling to achieve good coverage (for example, less than 70%), there are other tools to stop it, even under the overwhelming pressure to open borders.

You can make sure you still have enough investment in contact tracing and probably keep the requirement to wear a mask on public transport or limit the rally as it happens.

Some commentators have combined global herd immunity to Covid-19 due to a combination of reasons such as heterogeneous vaccine deployment, DPT vaccine efficacy, new variants that evade immunity, and the potential for lasting immunity. Already claims that it is probably impossible. Is it really fantastic that the world could be truly “immunized” to Covid-19?

JP: JP: I think it’s too early to say this. I don’t know how well the vaccine works in the long run.

But it should not scare us into negligence or despair.

It joins the list of all other infections and sits in the spectrum with them.

Some of them, such as influenza, Ebola, Marburg virus, and to a lesser extent measles and whooping cough, still confuse us.

Then there are others who have been driven into lively debates about the horrors of the past. Consider polio and smallpox.

HPH: In terms of overall impact, you’ve learned from experience that vaccines often exceed expectations in the real world.

You can only make estimates and make various assumptions, but you may underestimate their effectiveness.

That said, we can overestimate it too, so we have to wait.

One thing for sure is that we need to set high goals.

JP: JP: It should be noted that we still have a health care system that is easier to overwhelm than in other countries.

Even without Covid-19 in the photo, we already have a population that is ridiculously and embarrassingly burdened with high infections.

The steps we took to reduce Covid-19 also had dramatic effects on other respiratory diseases such as influenza, respiratory syncytial virus (RSV), and whooping cough.

We hope that a glimpse of what we can do will inspire us and policy makers to maintain action to keep these diseases at lower levels throughout the population.