Singapore says COVID herd immunity cannot be achieved regardless of numbers vaccinated

 by Ganesh Sahathevan 

Singapore's Ho Ching on Facebook overnight:

Previously, there was a chance of herd immunity, bcos the R0 of older variants were like 2-3. This meant if we have 80% of population vaccinated with 90% effective vaccines, we would have a chance of herd immunity.

But Delta destroyed that dream of herd immunity.

The post in full 

HO Ching 

19h  · 

https://www.facebook.com/permalink.php?story_fbid=1868029236718235&id=100005335308340

Some folks ask about the projection that we will all meet the virus sooner or later.

My apologies if that sounds scary.

With vaccination, we can be more relaxed about meeting the virus.

For the old folks, vaccination plus booster shot is even better, bcos it reduces the chances of getting infected, and greatly lowers the risks even more of getting seriously sick or dying too.

As the saying goes:

What doesn’t kill us will make us stronger.

And vaccination helps reduce the chances of Covid killing us, so meeting the virus sooner or later means we get stronger.

I’d just explain why we do expect to meet the virus sooner or later, perhaps as fast as 3 months, or perhaps as late as 6 or 9 months if we collectively work to slow the spread.

Why would we all meet the virus sooner or later?

The first most important reasons:

Delta is highly infectious.

None of the vaccines we have in the world today can provide high protection against infection.

This means everyone will meet the virus sooner or later. Everyone.

[[[For those not interested in the numbers, can skip pass tobthe end of this triple square bracket section.

For those interested in numbers,

we know the infectiousness of Delta aka R0 is 5-8.

On average, a Delta case infects 5-8 others.

To have herd immunity, we will need to have 100% of the people vaccinated with vaccines which can prevent 80-90% of the people; or we have to vaccinate 90% of the people with vaccines which have 100% effectiveness against being infected, and not just being infected with symptomatic illness.

So, clearly, none fo the vaccines available today anywhere in the world is so effective against Delta.

Previously, there was a chance of herd immunity, bcos the R0 of older variants were like 2-3. This meant if we have 80% of population vaccinated with 90% effective vaccines, we would have a chance of herd immunity.

But Delta destroyed that dream of herd immunity. ]]]

We know, even for Delta, we will be much better protected against serious or fatal infection if we are vaccinated. Vaccination will reduce the risks of dying for adults and esp old folks to risks of dying from a flu.

For our old folks, we are giving a 3rd shot booster - this will help drastically reduce their risk even further of getting infected in the first place.

We can slow down further by having dining restrictions to reduce prolonged mask down makan and drinking.

That slows the speed of spread, but does not reduce the risk if we do get infected.

But if we already have been vaccinated, the infection will have the effect of boost to our immune defence training if it doesn’t kill us.

With the 3rd shot booster, we would reduce the risks of death even lower, and so meeting the virus will mostly help to test and make our immune response even stronger.

So what does not kill us will make us stronger.

And our vaccination, AND our 3rd shot for our older folks, will make us much much less likely to be killed.

And so we don’t need to fear the virus, and should think of infection as likely to make us stronger esp if we are young.

It’s better to know that we will all eventually meet the virus - it’s a question of sooner or later, and nothing to fear if we have been vaccinated.

So why the cha cha cha backwards one small step to stop at 2 for dining out?

This is simply an added move to slow down the speed of increase of cases.

For now, we are simply trying to make sure the hospitals are still able to treat all patients and not just be overwhelmed by Covid patients.

Unlike the India, UK, Indonesia, USA, Brazil, Israel, or elsewhere last year and early this year, our population is highly vaccinated and hence highly protected against even the Delta.

But Delta spreads faster than the old variants.

The current vaccines are good but not good enough against the Delta in terms of preventing infection.

So if we don’t slow down the spread, we will overwhelm the hospitals and that would leads to more preventable deaths from other causes and not just from Covid.

So bear with this till our heroic folks working in the background can get their backend support sorted out.

There is an urgent need for more medical personnel.

So trained doctors and nurses, medical and nursing students, and retirees and private sector practitioners, please contact MOH to volunteer.

The rest of the stuff are straight forward to set up, whether to expand call centre lines, to increase hospital beds, to set up CTFs and CCFs, etc.

But the bottleneck will be doctors and nurses if we have to deal with a caseload of say 10,000 cases a day, as some modelling suggested.

This is also why the MTF made a hard call to cha cha cha back to 2 pax dining out.

Next question is:

Is this flu or not?

Yup, it is NOT flu.

Covid is Covid, and flu is flu (although there are many types of flu).

But countries like Norway are treating Covid like flu!

What does that mean?

Actually, the confusion is about risks.

With vaccination, we reduce the risk of death from Covid to be like the risk of death from flu, esp for old folks.

In other words, governments like Norway and others are saying, we now no longer need to be frightened of huge numbers of deaths of suffering from Covid, bcos we have vaccination.

So from the individual perspective, we can treat Covid as not a very big deal if we are vaccinated.

Pfft! 2 shots of vaccines and we are highly protected against serious illness of death, esp if we have the better types of vaccines.

And Covid was never as dangerous for young kids,compared to flu in young kids.

So if we are not frightened about flu in young kids, we should be less frightened about Covid in young kids.

Studies also show that so called long covid type symptoms between infected young kids and uninfected young kids are the same.

So Covid in young kids is not a key driver for Long Covid type symptoms.

Ah ok - risk of serious illness or death for young kids, or risk of Long Covid are both practically zero.

Yes, yes, Covid can still be dangerous to kids with leukemia and the very obese kids. But otherwise, the risks are practically zero.

As risks of death doubles every 5-8 years, parents should worry about their own risks if they are not vaccinated.

So when we say treat Covid like flu, we don’t mean we treat Covid medically like flu, or we treat covid like flu from a public health mgt.

How come?

Medically, the medication for treating flu is different from treating covid.

A flu virus is among the smallest virus.

A covid virus is among the biggest virus.

The way they infect our cells is different. So the drugs are different.

But other consequences of flu or covid, like pneumonia, are more general, and can be treated with similar protocols like giving oxygen or putting on ventilators to helping breathing, etc.

We now have good news about antiviral medication or antibody cocktails that are now under trials, or being scaled up for production.

These are still limited by production, but we should see supply go up end of this year or early next year.

Public health wise, covid is very different from flu.

The infectiousness of flu is about 1.2~1.4, half the infectiousness of even the old covid variants last year.

But Delta has an R0 that looks closer and closer to 8.

This means the spread is super fast.

One modelling for people who are unvaccinated and hence vulnerable to infection shows that 75% will be infected in 3 months if we assume an R0 of 4.

So if we are not careful, we can overwhelm out hospitals, bcos a small percentage of a large number is a large number.

But, but, but why do other countries seeing falls in cases when their vaccination rate is lower?

One simple answer is that these countries all have seen huge multiple waves before, and so their background immunity from past infection is much higher than in Sg.

But, but, but what about those without big waves still have small numbers.

This is really a case of luck, plus various lock down measures.

Why luck?

Based on last year’s variants, some 70% of the cases do not transmit anyone else. And some 10-20% are responsible for 80-90% of the secondary transmission.

So if we are unlucky to have a superspreader cluster like Jurong Port, then we can spark a huge run, bcos of the hidden connectivity to all parts of Sg

If we have a superapreader cluster in a school, or KTVs, chances are we would be able to test, and trace the contacts to close down the spread.

That’s it, folks.

Below is a chart from the smallish dataset in Sg giving a sense of the exponentially increasing risk with age, with or without vaccination.

Without vaccination, the curve rises steeply with age.

With vaccination, each point is reduced, but the curve still goes up though not as sharply as for the unvaccinated.

And the booster 3rd shots is to reduce the risks even more at the older end of the curve to flatten the risk.

In other words, pls relax if you and your teens and adults in the family are all vaccinated.

And if you wish to protect the elders at home or in the neighbourhood, all of us, not just the old ones should reduce our makan and kopi outings.

Chart courtesy of Business Times team who converted MOH data into a simple easy to understand chart below:

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