Should we be concerned about the delta variant?

This article uses data from Public Health England and the Centers for Disease Control and Prevention of the US to shed more light on the delta variant.

When you listen to the news and social media, a continuous report of how the delta variant is “highly contagious,” killing the unvaccinated.

The punchline, of course, is that everyone should “do their part” or be “patriotic” and get vaccinated.

But is it really? Is it possible that the SARS-CoV-2 is mutating into a more dangerous form that will eventually wipe out the unvaccinated? And then transmitted the dreaded variant to the vaccinated?

Let’s look at epidemic histories.

Humanity has encountered pandemics before that have killed many. The table below from Wikipedia shows a partial list of epidemics that have killed more than a million people.

The list contains different bacteria and viruses, where the epidemics happened, and the number of deaths. Common to all is that there is a start and end date. Deadly epidemics always end. If not, we will not be here anymore.

Even the influenza virus, which is notorious for constant mutations, also has an end, as exemplified by the influenza pandemic from 1949-1958, as shown below.

Reported cases of influenza in American countries for the period 1949–1958, illustrating the severity of influenza A virus subtype H2N2 pandemic in 1957. Source: Wikipedia.

Pandemics end for many reasons. Herd immunity, migration, lifestyle changes, and public health policies can all contribute. This article will highlight viral mutation as one reason.

Viral Mutations and Virulence

Viruses are made of a core of genetic material surrounded by protective protein. The genetic material can be DNA or RNA in the case of coronaviruses.

Viruses go inside the host cells and use them to replicate or make copies of themselves using the cell’s machinery.

During the replication process, changes or mutations in the viral genome can happen. These mutations change the properties of the viruses.

Let us concentrate on one property change. Virulence or how deadly is the virus. Mutations can make the viruses more or less virulent to humans.

Scenario 1: SARS-CoV-2 mutation becomes more virulent.

If the SARS-CoV-2 becomes more virulent, three things can happen to the patient. The first is that the person will feel very sick that they won’t get out of the house. Second, the sick patients will be sent to the hospital, or third, they will die.

Whatever choice, that sick person will be isolated from other people because healthier people will try to avoid them or do something to protect themselves, like wearing a mask, putting on gloves, or washing their hands after touching them.

If they get admitted to the hospital, the sick COVID-19 patient will be isolated, and the medical personnel will be wearing protective personal equipment. There will be an attempt to treat the patient.

Now the patient may survive, which means the viral load will be lowered or eradicated by the immune system. If the unfortunate patient dies, then they get cremated or buried.

The common thing is that the sick person with the deadlier strain gets isolated from healthier people, and the virus does not spread.

Scenario 2: The mutation leads to a less virulent variant.

If the SARS-CoV-2 changes to a less deadly form, then several things can happen too. One is that the person will have mild symptoms. Second, the host’s immune system will be able to take care of the infection.

If the COVID-19 symptoms are mild, the host may deny that he is sick, not seek medical consultation, and continue working or going out with his friends. People around him may not identify him as being sick with Covid-19 and therefore not protect themselves.

What’s the bottom line with the less virulent variant? That variant spreads more easily or becomes more contagious, and in that case, numbers for that particular variant increase.

That reasoning may sound logical, but where is the proof? Let’s look at some data from Public Health England and the Centers for Disease Control of the U.S.

This data came from The SARS-CoV-2 variants of concern and variants under investigation in England. Technical briefing 16. 18 June 2021click on the link to see the pdf. The table below is from page 8.

From the table, you can see the Case Proportion of the delta variant is second at 21.1%. While Alpha, the leading variant, is 77.9%

Case Fatality is the ratio between deaths and confirmed or reported cases of a specific disease. COVID-19 in this situation. The case fatality for the alpha variant is 1.9%, and for the delta, variant is 0.1%.

The alpha variant is 19 times more deadly than the delta variant. (1.9% alpha/0.1% delta). The Case fatality among those with 28-day follow-up is 2.0% for the alpha and 0.3% for the delta. The delta is 6.67 times less deadly than the alpha variant among those with 28 days follow-up.

It is of note that the Eta and Beta variants have a higher case fatality compared to the delta variant (Eta 2.7%, Beta -1.4%, Delta – 0.1%)

With the Eta and Beta being deadlier, both have a lower number of people infected or lower case proportion compared to the Delta and Alpha (Eta 0.2%, Beta 0.3%, Delta 21.1%, and Alpha 77.9%)

Therefore, the U.K. data supports the theory that viruses that tend to mutate to a less virulent form (Delta variant in this case) become more contagious and increase in number.

What about the reports that the unvaccinated are dying from the Delta variants?

This time we will use table 4 from page 12 of the same document, SARS-CoV-2 variants of concern and variants under investigation in England. Technical briefing 16.
18 June 2021.

Table 4 shows the number of unvaccinated and vaccinated people presented to the A&E or Accident and Emergency with delta variant confirmed cases. A&E is the equivalent of the Emergency Room in other countries.

The bottom row shows the number of unvaccinated and vaccinated patients with the delta variant who died.

I divided the deaths by the corresponding number of cases to come out with a percentage.

Unvaccinated 34/35,521 x 100% = 0.095%
Vaccinated < 21 days post-dose 1 – 1/4,094 1 x 100% = 0.024%
Vaccinated ≥ 21 days post-dose 1 – 10/9461 x 100% = 0.105%
Vaccinated ≥ 14 days post-dose 2 – 26/4087 x 100% = 0.636%

The calculations show that the unvaccinated have a lower percentage of deaths at (0.095%) compared to the vaccinated that are more than 21 days post-dose 1 (0.105%) and 14 days post-dose 2 (0.636%).

The vaccinated who are ≥ 21 days post-dose 1 are 1.1 times more likely to die from the delta variant of COVID-19. Equal to the unvaccinated.

The vaccinated ≥ 14 days post-dose 2 are 6.7 times more likely to die from COVID-19 than the unvaccinated.

Thus, the vaccinated who received 2 doses are more likely to die from the delta variant of COVID-19 than the unvaccinated in this UK report.

But that is the U.K., what about the US?

Delta Variants in Barnstable County, Massachusetts, July 2021

A CDC report, Outbreak of SARS-CoV-2 Infections, Including COVID-19 Vaccine Breakthrough Infections, Associated with Large Public Gatherings — Barnstable County, Massachusetts, July 2021 can give us an idea about the delta variants in the US.

469 cases of COVID-19

(346; 74%) of cases occurred in fully vaccinated persons
(119; 89%) had the (Delta) variant of SARS-CoV-2
274 (79%) vaccinated patients with breakthrough infection were symptomatic
Among five COVID-19 patients who were hospitalized, four were fully vaccinated
No deaths were reported. (Whew!)

Therefore, the US experience in Barnstable county, Massachusetts, in July 2021 showed that overwhelmingly more vaccinated people got sick and were hospitalized with the delta variant of COVID-19 compared to the unvaccinated.

Note: The CDC defines the vaccinated as those who had completed a 2-dose course of mRNA vaccine [Pfizer-BioNTech or Moderna] or had received a single dose of Janssen [Johnson & Johnson] vaccine ≥14 days before exposure)

Contagiousness of the Delta variant

The secondary attack rate is the number of new cases among contacts divided by the total number of contacts. T Secondary attack rate of the delta variant is higher than the alpha in both groups who have traveled and those who did not travel. (2.3% and 11.4% Delta) compared to 5.1% and 8.0% Alpha)

The findings that the vaccinated and unvaccinated can get the COVID-19 may be why the CDC changed the mask mandates for everyone.

Take Away Message

The UK and the CDC data show that the delta variant is more contagious but not deadly.

Why is it that more vaccinated people are getting the COVID? And why are they dying? – The answer will be in the next article.

Knowledge about Covid-19 is rapidly evolving. Information may update as new studies are made. Stay current by subscribing. Feel free to share and like.

Don’t Get Sick!

References:

Investigation of SARS-CoV-2 variants of concern: technical briefings. Ref: PHE publications gateway number GOV-9044PDF, 3.37MB, 55 pages.

Brown CM, Vostok J, Johnson H, et al. Outbreak of SARS-CoV-2 Infections, Including COVID-19 Vaccine Breakthrough Infections, Associated with Large Public Gatherings — Barnstable County, Massachusetts, July 2021. MMWR Morb Mortal Wkly Rep. ePub: 30 July 2021. DOI: http://dx.doi.org/10.15585/mmwr.mm7031e2

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