If we don't vaccinate, is it feasible to achieve herd immunity in the local setting?
Herd immunity is the resistance to infection provided by a community with members who are mostly already immune or protected from the infection of concern. The idea is that if an individual is surrounded by people who are already immune to a particular disease, the likelihood that he/she will be infected is minimal to nil.
The natural way today to achieve individual immunity is by being actually infected. However, this option carries with it the burden of the whole spectrum of the symptoms and complications of that disease. This is problematic for those with co-existing illnesses as the infection may trigger or aggravate their medical conditions.
The most practical way today is thru vaccination. The body’s immune system is triggered the way an infection would, minus the difficult symptoms and complications. However, immune-compromised individuals cannot readily get vaccinated. They can be overwhelmed by their body’s own immune response. This is where herd immunity comes into play. By being surrounded by immune individuals, the immune-compromised are afforded a certain degree of protection without the need to be vaccinated.
Not everyone can or want to be vaccinated though, believing that natural immunity through natural infection is best. While there are valid talking points in that idea, it is not practical in the local setting.
Let’s break down the numbers.
To establish an effective herd immunity, a certain percentage of the population has to be infected and subsequently survive. The percentage varies depending on the reproductive number (R0 or R naught) of the virus or its ability to be transmitted to infect others. The higher the R0, the higher the number of individuals needed to be immune for herd immunity to work. The previous variants of SARS-CoV-2 have an R0 of 2-3 so as low as 67% would be enough to have herd immunity. The Delta variant has an R0 of as high as 7. This means we need at least 86% of the population to be immune before we can have herd immunity.
As of 25 August 2021, the Philippine population is 111,249,116.1
If we want to have local herd immunity thru natural infection, at least 86% of Filipinos need to be infected and eventually survive COVID-19. That’s 95,674,240 individuals. As of 26 August 2021, DOH has recorded a total of 1,899,200 COVID-19 cases in the Philippines, or just 2% of the needed 86%.
It's irrelevant now to consider natural immunity because 17.5M have already received at least a dose of the COVID-19 vaccines. We can rephrase the question to "Is it feasible to achieve natural herd immunity from COVID-19 from here on?"
The recomputed number of Filipinos who need to be infected and eventually survive COVID-19 is now roughly 78M.
Around 15-20% of persons who test positive for SARS-CoV-2 will need hospitalization. This percentage goes up to as high as 40% if we look at the numbers of those with co-existing medical illnesses. If we want natural herd immunity, we would need to accommodate 12-31M COVID-19 cases. For easier computation, let's put it at 20M.
The estimated total bed capacity of Philippine hospitals in 2020 is 112,000.
A patient with COVID-19 will stay in the hospital for an average of 14 days.
Let’s assume the following:
- only COVID-19 will be admitted in all hospitals starting today
- the government healthcare and patient resources are inexhaustible
- individuals will only get infected and hospitalized once
- infections of individuals can be scheduled, i.e., we can decide when people can get infected
In that impossible scenario, it will take at least 7 years to accommodate all COVID-19 patients needing hospitalization. It will take that long to achieve herd immunity if we rely on natural infection alone. It gets worse.
Note that not all who will be infected will survive. The death rate of COVID-19 in the Philippines is 1.73%. This means that of the 78M who will be infected, 1,349,400 will die. They could be your family member, your friends, your co-workers, or you. How big is that number? Imagine the Philippine Arena with its seating capacity of 55,000. Imagine 24 of that. Filled to maximum seating capacity. Now imagine them all dying of COVID-19. But it doesn't end there. Remember that these numbers are based on several assumptions above.
In the real world, we cannot dedicate all hospital beds to COVID-19 cases alone. Current numbers indicate only around 30% at the most. This limits the number of patients who can be admitted. What happens to those who need hospitalization but cannot be admitted? The case of Claire dela Fuente comes to mind. She died in a tent outside a hospital waiting for a bed to be available to her. With more patients needing hospital beds which are no longer available, death rate goes higher. Add another Philippine Arena.
In the real world, the government healthcare and patient resources are limited. The government cannot subsidize the hospitalization of everyone. Majority of private patients won't be able to afford the bill on their own. What happens then? More unnecessary deaths. Add another Philippine Arena.
In the real world, patients can get infected more than once. The actual number of hospitalizations will increase beyond our estimate. The limited healthcare will be strained further. Patients who don't make it increase. Another Philippine Arena.
In the real world, we cannot decide when one will get infected. We cannot stop people from being infected when our hospitals are already full. We do not get to decide that people in certain regions get infected just because they still have a lot of empty hospital beds. The cases can go beyond our capacity. Add another Philippine Arena. Maybe two. Or three.
In the real world, herd immunity without vaccinations is inhuman. To push for it is simply murder.
If you live in the real world and not in some fantasy or parallel dimension, get vaccinated if you have no valid medical reason not to have it.
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