Waiting for vaccine or herd immunity?
HOW many lives are we willing to lose to the coronavirus disease (Covid-19) to achieve “herd immunity” which sets in when a large number (50-67 percent) of the population left standing have developed resistance from their exposure to the virus?
By that time, those who were high-risk because their immune systems were weak and could not fight back on their own have died. But the remaining members of the herd would have gained immunity and a better chance of surviving as the virus petered out.
The body exposed to a virus makes antibodies to fight back. When it recovers, it keeps the antibodies to repel a new attack. Two years after the 2015 Zika virus outbreak in Brazil, an estimated 63 percent of the population had had the exposure that gave them immunity.
As of Sunday, the Covid-19 pandemic had infected more than 10.3 million people worldwide, killing at least 504,000. Spikes were noted where officials were tempting the fates with their politicized actions and disregard of accepted quarantine rules.
Our local Covid-19 scoreboard showed 35,455 cases as of Sunday, 653 of them new infections, and 1,244 total deaths, eight of them reported that day. It was not clear if the apparent rise in cases was due to better testing or the relaxation of quarantine protocols.
To answer our question in the head, nobody is waiting for herd immunity to set in.
While sending his generals and “civilians in white gowns” to fight the contagion, President Duterte looks more like he is anxiously waiting for an anti-Covid vaccine to be developed by friends. It may be a long wait, however, with experts saying it could take about a year.
The Department of Health said on Friday, meanwhile, that doctors may send home patients who do not show Covid-19 symptoms for 10 days. The advice was based on what the DoH said were medical studies and scientific articles.
This protocol jibes with the World Health Organization’s criteria announced June 17 for discharging asymptomatic patients without requiring testing 10 days after being diagnosed positive for Covid-19.
• Covid recovery chances have improved
WE share below encouraging Covid-19 notes of our brod Ernie Salas posted on the Pinoy ’55 chat site.
In the ongoing Covid-19 pandemic, there is a greater chance of survival for those getting infected now, in June, than those who got it earlier in February. Doctors and scientists know more about Covid-19 now than four months ago and hence are able to treat patients better.
These are some of the important things that we know now that we did not know in February:
1. Covid-19 was initially thought to cause deaths due to pneumonia, a lung infection, and so ventilators were used to treat patients who could not breathe. Now we are realizing that the virus causes clots in the blood vessels of the lungs and other parts of the body, causing reduced oxygenation.
Now we know that just providing oxygen by ventilators will not help but that we have to prevent and dissolve the micro clots in the lungs. This is why we are using drugs like Aspirin and Heparin (blood thinners that prevent clotting) as a protocol in treatment regimens now.
2. Patients used to drop dead on the way to the hospital due to reduced oxygen in their blood – oxygen saturation. This was because of Happy Hypoxia (more properly called “silent hypoxia”) where even though the oxygen saturation was gradually reducing, the patient did not have symptoms until it became critically less like sometimes even 70 percent.
Normally we become breathless if oxygen saturation drops below 90 percent. This breathlessness is not triggered in Covid patients and so we were getting the patients very late to the hospitals in February. Now since knowing about Happy Hypoxia we are monitoring oxygen saturation of all Covid patients with a simple home-use pulse oximeter and getting them to the hospital if their oxygen saturation drops to 93 percent or lower. This gives more time for doctors to correct the oxygen deficiency in the blood and a better survival chance.
3. We did not have drugs to fight the coronavirus in February. We were only treating the complications caused by it… hypoxia. Hence most patients became severely infected. Now we have two important medicines – Favipiravir and Remdesivir – which are antivirals that can kill the coronavirus.
By using these two medicines we can prevent patients from becoming severely infected and therefore cure them before they go to hypoxia. This knowledge we have this June, not in February.
4. Many Covid-19 patients die not just because of the virus but also because of their own immune system responding in an exaggerated manner called Cytokine Storm. This stormy strong immune response not only kills the virus but also kills the patient.
In February we did not know how to prevent this. Now we know that easily available medicines called Steroids, that doctors around the world have been using for almost 80 years, can be used to prevent the Cytokine Storm in some patients.
5. Now we also know that people with hypoxia became better just by making them lie down on their belly, in prone position. Apart from this, a few days ago Israeli scientists discovered that a chemical known as Alpha Defensin produced by the patient’s white blood cells can cause the micro clots in blood vessels of the lungs and that this could possibly be prevented by a drug called Colchicine used over many decades in the treatment of gout.
Going forward, there’s nothing to panic about Covid-19 if we remember that a person who gets infected later has a better chance at survival than one who got infected much earlier.