Hello and welcome to my channel Medicine with Dr. Moran. I'm Dr. Keith Moran. The
CDC is finally acknowledging the power of natural immunity! The CDC released a report this week on
Covid-19 cases and hospitalizations by vaccination status as well as previous Covid-19 diagnosis.
This allows us to compare vaccinated immunity to natural immunity. It was based on a large
number of people in California and New York state between May 2021, and November 2021.
The study was conducted at the end of the Alpha variant wave and during the Delta wave in these
two states and the two states make up 18% of the total U.S. population. The CDC researchers
looked at four groups of people. The unvaccinated with no previous infection, the vaccinated with
no previous infection, unvaccinated with previous infection, and vaccinated with previous infection.
They then looked to see who developed Covid-19 in both states.
In addition in California they also looked at hospitalizations.
Now to the results. Now during the time period they compared unvaccinated people with no previous
infection to the other three groups. This group was considered the baseline. First they looked
at new Covid-19 diagnoses. This slide shows the results. Again the first group at the top who were
unvaccinated and had no previous infection served as the baseline. The second group which was the
vaccinated group with no previous infection now this group was made up of people that either had
two MRNA vaccines or one J & J. As you can see this particular group had a 6.2 fold lower risk
in California and 4.5 fold lower infection rate in New York state of a new diagnosis of Covid.
The third group which was the unvaccinated group with previous infection or recovered
or natural immunity had a 29-fold lower risk in California and 14.7 fold lower risk in New York.
The last group was the vaccinated group with previous infection in other words hybrid immunity.
They had a 32.5 fold lower risk in California and 19.8 fold lower risk in New York state.
So if you take in this slide all four groups you can see that the lowest risk of Covid-19
infections occurred in the vaccinated group who also had previous infection
which is called hybrid immunity. They had slightly better reduction
than the unvaccinated previously infected group however this was not statistically significant.
Now the third group which was the unvaccinated previously infected group or natural immunity
had much more significant reductions in both California and New York state than the people
who were vaccinated with no previous infection in this analysis. This slide from their study looks
at the entire time frame of the study from May until November for the California study subjects
and it plots all four groups on the graph. The dark blue line which is above the other three
lines represents the rate of Covid-19 cases in the unvaccinated with no previous Covid-19 diagnosis
which was the baseline group number 1. The light blue hash line represents group 2, the vaccinated
no previous infection and the other two lines which are essentially superimposed on each other
are the unvaccinated previously infected ie natural immunity and the vaccinated
previously infected ie hybrid immunity. So you can see on this graph the significant reduction
in infection for the three groups compared to the unvaccinated uninfected group in dark blue.
You can see that the people who have had previous Covid-19 infection whether they've
been vaccinated or not had the lowest rates of new Covid-19 infections during the study.
Next I want to show you the same graph from New York state. This is very similar to the California
graph and again shows the much higher rate of Covid-19 infection in the unvaccinated uninfected
group 1 compared to the other three groups. Again it demonstrates that people with previous
infection whether vaccinated or not had the lowest rates and were essentially superimposed.
The vaccinated group with no previous infection had a slightly higher rate of Covid-19 infection
just like in the California group of patients. Next I want to show the hospitalization rates
for all four groups. This was only done for California and here are the results. Group
1 the unvaccinated with no previous infection again was the baseline. The people that were
vaccinated with no previous infection group 2 had a 19.8 fold lower risk of hospitalization and the
unvaccinated previously infected group had a 55.3 fold lower risk of hospitalization and lastly
group 4 the vaccinated with previous infection had a 57.5 fold lower risk of hospitalization.
This slide shows the same kind of results that we saw for the reduction of infection in both
New York and California. So basically the worst group to be in of course was the unvaccinated with
no previous infection and that's a group with no immunity. The lowest risk score of course
were those that had a previous infection whether vaccinated or not in other words group 3 and group
4 they're essentially superimposed. Now there was a significant reduction in
hospitalization in those people who were vaccinated without previous infection.
So what all this data is telling us is that it's important to have immunity. You obviously either
get this through vaccination or from being infected. If you have immunity you're much
less likely to get infected or hospitalized with the virus. Now this is really important if you're
older or have comorbidities. I've presented many studies on my channel about natural immunity.
In fact on YouTube I don't think you'll find a channel that's gone into the depth and showed
as many studies on natural immunity and these studies have shown that it's at least as good as
vaccinated immunity with some studies showing that it's actually statistically better. We'll link to
the playlist on natural immunity down below in the description and up above. This particular video
which I made Systematic Review of Natural Immunity is a recent state of the art review on the major
studies looking at natural immunity. There's a link below to the video in the description.
Today's study I'm reporting on suggested that at least during this time period of May to November
in New York and California the natural immunity was better than vaccinated immunity. I have two
more slides to look at which look at each state and the vaccines that were given and subsequently
what happened with Covid-19 infections. This shows the rate of infections with no previous
Covid-19 or J & J in the blue line followed by the gray line which is no previous Covid-19
and Pfizer vaccinations then with lower numbers no previous Covid-19 with Moderna vaccination.
These three lines are all higher indicating more infections than the last three lines I'm going
to talk about. The lowest rate of infections on the graph are people all who had previous Covid
infections and were vaccinated. The yellow line is if you had a previous covet infection with
J & J and the blue and green line is if you had previous Covid-19 and Pfizer vaccinations
and the blue line is previous Covid-19 and Moderna vaccinations. The next graph is from
New York state. The data here mirrors what we just saw in California with the highest rates
of infection in the unvaccinated J & J group in blue again and the gray and yellow lines
indicating no previous infection and vaccination with either Pfizer and Moderna respectively.
The lowest three lines again were people who had hybrid immunity.
They either had previous infection and had J & J or previous infection with Moderna or Pfizer.
There were a number of limitations in this study and it's important to point these out.
That's often overlooked. It's an observational study. Obviously people weren't randomized to
vaccination versus no vaccination if you were previously infected or not previously infected.
Now because it's clearly an observational study it's not as powerful as if it was randomized.
Now it brings up an important point that the method of the study is actually the
most important part of any clinical study although it often never gets mentioned
because limitations can cast doubt on the results of any study. I've previously talked on this
channel two studies produced by the CDC which had significant limitations on this particular topic
both of which suggested that natural immunity was not as good as vaccinated immunity
despite many other studies to the contrary. In medicine we like to look at all of the studies
that we have hopefully they're similar and put them together often in a meta-analysis.
This is one of the ways that we can make decisions on how best to treat our patients. These two CDC
studies were picked up by the media and by people who commented on my video and it illustrates why
it's so important to critically appraise the medical literature which is something that
I've talked about before on my channel and it's something that's been occurring a lot during this
pandemic. A sentence or two out of the conclusion paragraph of the abstract of a study can become
a very active sound bite that gets virally spread without putting proper clinical appraisal to it
context is crucial. Physicians of course like myself are trained to critically appraise
the literature and to question the literature and biases that we have. This is why the peer
review process is important in publishing medical studies. At a doctor's journal club for example
we would all read a study such as this ahead of time then spend 60 minutes discussing different
aspects of it what was good what was not so good. While it may seem boring these are the things that
allow us to move forward in medicine rather than simply believing the conclusion of an abstract
and reporting on it on the internet or on other media. The other limitations are that it occurred
primarily during Delta and not during Omicron. It was also conducted before booster vaccinations.
They also did not stratify the results by time since vaccine receipt and there was no information
on the severity of the initial infection. It most importantly does not account for the full range
of morbidity as well as mortality in other words symptoms illnesses and death which are represented
by the groups who went through previous infections. This is an important point to make
however as the researchers point out the safest way to get immunity is through vaccination. This
is very important. Now this is an important point especially if you're older or have comorbidities.
So this study is another study that shows the strength of natural immunity.
Remember with natural immunity you make antibodies not just to the spike protein
but to other components of the virus as well as memory cells both B and T cells to parts of the
whole virus not just the spike protein. It's not clear at this point what the long-term protection
will be like for people with natural immunity or vaccinated immunity. The hope is that memory B and
T cells that develop from the vaccine or natural infection will protect against severe disease
for many years to come. This will obviously depend upon how the virus evolves. It may
not without periodic boost in immunity either getting reinfected or a vaccine boost protect
well against minor symptomatic infection. This in fact is the case with a lot of common cold viruses
that we've all come into contact with over the years. With the common cold of course we develop
long-lasting memory cells which ultimately protect us against severe infection and death but once our
antibody levels from that infection starts to drop down we can get reinfected with that same virus
months or a few years down the road and then of course you get common cold symptoms from that
make an announcement starting this week I'm going to devote more time and streamline how I make my
videos so I can provide more videos succinctly of course and much faster in order to provide the
most accurate up-to-date covid developments if you like my channel and videos like this
please subscribe. Please feel free to share with your family and friends. Most of the videos on
my channel are actually about Covid and this is primarily because I started my channel around
the same time as the pandemic began. Thanks a lot for joining me today on Medicine with Dr. Moran
I'm Dr. Keith Moran. and don't forget to get healthy if you're not and please stay healthy.