Hello, welcome to my channel medicine with Dr. Moran. If you've not been here before I'm Dr Keith Moran.
I'm a specialist in General Internal Medicine
The CDC and news outlets say that previously infected unvaccinated people are twice as likely to catch Covid than previously infected vaccinated people.
How do we know if this is true?
In this video I will review the new study everyone has been talking about from the state of Kentucky in the United States.
You cant just jump on the results of one small study that's what this is.
Even the people who performed and authored the study said that there were five significant limitations.
That's what the news nd the CDC are doing by ignoring the limitations.
As I mentioned before this kind of research is very important as many people throughout the world have recovered from the viral infection that we know as Covid-19
Thus they have developed natural immunity.
As of August 21, 2021 there have been 211,000,000 infections worldwide and unfortunately 4,400,000 deaths.
Understanding what happens with natural immunity is important because this allows us to decide and prioritize in a given population how vaccines should be distributed.
There's no question that there's still clinical debate as to which is better vaccinated immunity or natural immunity.
and of course there's debate on how long a reasonable level of immunity lasts.
Recently there have been news reports as well as information from the CDC that vaccinated immunity is better and so everyone should get vaccinated.
There were many news reports and there's a link to this one in the description.
The problem with news reports is that they neglect to comment on all of the limitaions of this particular study.
The study authors mention all of them for those who can't critically appraise medical literature.
but the limitations did not seem to make it into any of the news reports. Obstensibly because the reporters must not have really read the study and just read the conclusions or the summary.
They have been basing this on a observational study on a small number of people in Kentucky. There is a link below in the description.
I did get several comments about this study on one of my recent videos.
I want to describe the study to you. It was a case controlled observational study which means they chose people who had been previously infected and got re-infected.
They compared them to another group which had been previously infected and did not get re-infected.
The number of people in both groups were small. There were 246 patients in one group and 492 in the other.
They tried to match the groups up by sex, age, and time of initial infection as well as the diagnosis which is always a difficult thing to do after the fact.
This was essentially the summary. They said that being unvaccinated with previous Covid infection was associated with 2.3 times the odds of reinfection compared to being previously infected and then vaccinated.
Thus they state that all eligible people should be offered vaccines even those with previous infection.
What did not make it to the news reports were the limitations. I'll tell you about those brefly.
They pointed out five limitations to the study.
First of all it was a study done from a single state over only two months with a small number of people
They tried to match the two groups up it's obviously difficult and often there are unknown confounders that might be present when that occurs. They also point out that reinfection was not confirmed through whole genome sequencing to definitively prove that re-infection was caused by a different virus compared to the original infection.
Another limitation was people who have been vaccinated are possibly less likely to get tested. So you may have seen fewer infections in that group because they were tested less often.
Vaccination data may be missing for some people because vaccine doses administered at federal or out of state sites are not typically entered in the database they used.
This is why it's important that there's critical appraisal of medical studies. As you can see there's so many problems with this study that it's hard to believe the conclusion.
This is why we have a peer review process in place that primarily weeds out poorly done studies that are submitted for medical publication.
Critical appraisal of medical studies is something every medical student learns about nowadays.
I was fortunate in my training to learn from the pioneers in this area, Dr. David Sackett and Dr. Gordon Guyatt who were general internal specialists
who had interests in Epidemiology.
The work that they did and other Epidemiologists did at Mc. Masters University in Hamilton revolutionized the way that doctors look at medical studies.
They used the term Evidence Based Medicine. To me I cringe when people say "follow the science"
Looking critically and appraising medical research in a evidence based way is important and necessary.
I much prefer the term Evidence Based Medicine because we're talking about medicine.
So to summarize the Kentucky study the information really cannot guide us.
I'm not saying that there may be benefit from vaccinating people who have had Covid but this study certainly cannot be used to make that argument
as the media has attempted by making the assumption here as a forgone fact.
In fact there's some evidence from the Israeli Health Ministry. I can't independently verify or find which comes to the opposite conclusion during the Delta surge.
It's been widely reported that out of 835,792 Israelis who previously recovered from a previous Covid-19 infection they had 72 reinfections. Which is 0.0086%
compared to 0.057% of people who were vaccinated and got infected.
Thus Israelis who were vaccinated were 6.7 times more likely to get infected after full vaccination vs natural infection.
Health experts in Israel have been reported to be somewhat divided.
Some saying the data provides a higher level of immunity from natural infection while others remain unconvinced.
My position is that a single vaccine after a Covid infection will definitley boost your immunity with much higher antibody levels than you'll see in anyone who's had two vaccinations.
I made a separate video on this.
For people who are concerned or who have comorbidities a single vaccination makes sense. Particularly if your antibody levels are low.
but I always encourage people to discuss their specific circumstances with their healthcare provider to make an appropriate decision.
Of course it's very easy to say that antibody levels decline with time and so get vaccinated and boost your immunity and vaccinate every so often.
But what we really want to know is whether vaccination after natural infection, we call it Hybrid Immunity
is beneficial looking at clinically relevant metrics.
What I mean by this is looking at if it prevents hospitalization and death.
The purpose of immunity here whether it be vaccinated or natural immunity is to turn Covid-19 into an asymptomatic or minimally symptomatic one that you can easily manage at home
There may be risks of a third vaccination and it's not targeted to any of the variants such as Delta.
I point out that there was a significant incidence of Myocarditis after the second injection of Pfizer in young males.
So studying the third dose is going to be important and its going to be easy considering the number of people we have.
I've mentioned this in previous videos.
You can take a group of people who have been previously naturally infected and randomize them to a single vaccination and the other half to no vaccination and follow them for a period of time.
The same can be done with non-immunocompormised people who have never been infected but have been fully vaccinated.
and you randomize those people to a third injection or no third injection and see what the results are.
This type of medical research is important. Hopefully we will have some information on this in the coming months.
Thank you for joining me today on Medicine with Dr. Moran. I'm Dr. Keith Moran. Remember to get healthy and stay healthy.