HERD IMMUNITY?

Vaccination is the medical sacrament corresponding to baptism. Whether it is or it is not more efficacious, I do not know. ~ Samuel Butler  

Emus no longer fly higher than we humans’ realistic hopes for attaining global herd immunity from the SARS-CoV-2 virus.

Herd immunity refers to the level of protection from an infectious disease – like covid-19 – that occurs either when a sufficiently high proportion of a human population can no longer acquire or transmit infection, or when immunity resulting through vaccination or previous infection has been attained. Reaching this threshold level of protection is crucial.

Emus, a herd of which is shown below cavorting in their native Australian outback, do not fly. However, they can run as fast as 30mph. But, being appropriately adaptable on six different occasions during their 10-million year stay here on Mother Earth, emus apparently have to been able to fly, then abandoned flight and later relearned how to use their wings for liftoff. Impressivo. Do emus enjoy herd emunity? That is not yet known. 

A herd of emus in the outback. With herd emunity?

In early 2020, at the height of initial pandemic anxieties, the CDC and other public health authorities proclaimed herd immunity as a goal for its efforts to curtail the spread of SARS-CoV-2, aka covid-19. Early on, when asked about covid herd immunity, the CDC said it was possible after about 60-70% of all of us are immunized and behaving appropriately.

Through last spring and fall, the CDC emphasized attaining herd immunity. It no longer does. This puzzling change acknowledges a shift in epidemiological thinking. Several intervening factors likely make attaining herd immunity an uncertain prospect at best, and realistically unlikely any time soon.

These factors include: the uneven vaccine rollout, together with some people’s persistent, “unscientific” hesitancy about getting inoculated with a vaccine and widely-circulating coronavirus variants, like B.1.1.7 here in the US.

Such covid variants have been completely expected. It’s what viruses do. Unfortunately, every virus does its best to lengthen its effective life-cycle by always producing mutant variants (also called strains). Some strains are more contagious and/or lethal, others are not.

The annual flu vaccine “booster shots” that we’ve been living with since 1945 attest to such variants. Each year’s booster shot for flu is different, depending on the latest variants. Despite the shots, on average the flu kills 36,000 people in the US per year.

According to the FDA, the 2020-21 seasonal influenza vaccine formulation will likely cover four viral variants: an A/Hawaii/70/2019 (H1N1) pdm09-like virus; an A/HongKong/45/2019 (H3N2)-like virus; a B/Washington/02/2019-like virus and a B/Phuket/3073/2013-like virus (B/Yamagata lineage).

So now you know and can ready your arm for flu shots beginning in October. Interestingly, last year’s flu season was unusual in that flu cases began to decline in March. According to the CDC, this was “perhaps associated with community prevention measures for covid-19.” Thank goodness for small favors.

But back to our current nemesis, covid-19. Contrary to the media’s hype – the multitude of misbegotten headlines about “conquering covid” – after the first covid vaccines became available last December, the covid-19 virus will not be defeated any more than the typical flu virus has been.

There won’t be a “one and done” covid vaccine. The covid-19 virus will very likely need to be “managed,” like every other dangerous virus has been for over 200 years. Depending on how long immunity lasts, each of us should expect to receive periodic (possibly annual) covid-variant-based booster shots.

On May 3, Dr. Anthony Fauci himself dismissed the relevance of herd immunity as a goal, saying “People were getting confused and thinking you’re never going to get the infections down until you reach this mystical level of herd immunity, whatever that number is.” Mystical; that’s nice word-play Dr. Merlin.

On May 10, Jeffrey Zients, the White House Covid Coordinator, stated instead of reaching herd immunity, the goal should be to achieve some sense of normalcy by getting 70% of Americans immunized. Ah, normalcy. But does it beat herd immunity? More to the point, what exactly does “normalcy” mean?

Dr. Fauci and Mr. Zients are casting mistargeted aspersions. We vaccine-recipients and non-recipients ourselves were not “getting confused.” We are being excessively aided in our confusion by experts like yourselves who have been broadcasting differing, inconsistent stories about covid’s apparently-mystical herd immunity, and its threshold level. If anyone is confused, it’s been the experts. Not us.

Some doctors have said the covid herd immunity threshold (HIT) rate – the immunization level required to provide general, overall population protection – is about 60-70%, as mentioned above. Other epidemiologists have estimated the covid HIT rate is more likely 80-90%.

After months of emphasizing it, experts like Dr. Fauci are now shelving herd immunity as a goal for covid control. My bet is they’re now dismissing herd immunity because it cannot be realistically attained. Reaching herd immunity across Earth’s seven continents is even more next to impossible.

If we can somehow now become convinced to forget about herd immunity and instead believe in attaining “normalcy,” public health experts and administrators could eventually be judged victorious.

For other infectious diseases, attaining their HIT rate has been successfully accomplished. Measles’ HIT rate is an unmystical, but high 95% due to its significant contagiousness. Like other transmissible diseases, measles has been around for a long time. The measles virus moved from livestock to humans roughly 4000 years ago. A vaccine was introduced 58 years ago, in 1963. This vaccine remains 99% effective.

The measles, mumps, rubella (MMR) vaccine is administered to young children, as you may know or even remember. The CDC has declared 90.8% of US children by age 24 months have been immunized for MMR. In 2019, there were just 1,282 individual cases of measles throughout the US. Victory! Nevertheless, about 1.3M people die from measles annually across the globe.

Since Jan. 1, 2021, 3.2M deaths have occurred worldwide from covid; just over 581,000 in the US. As of May 11, 35% of Americans are fully vaccinated.

No matter how mystical it might be, public health authorities should continue wrangling to reach herd immunity for the covid-19 virus, not just whatever normalcy may be. They possess vital medical and social obligations to do so. Attaining the final percentages of immunization for the US covid HIT rate will be challenging and involve disproportionate expense and time. Is that extra expense worth it? Folks including the president will have to decide when to declare relative “success,” but it isn’t going to be soon.