hey guys welcome to another video my name is dr mike hansen and in this video i'm going to
try to answer as many questions i can about level of protection versus the delta variant
so there are a lot of factors that determine how protected you are
against the delta variant for example have you had the vaccine if so which one have you
had did you have covid already did you have the covid vaccine and covid infection
are you immunocompromised if so did you get the booster shot already what if you had the vaccines
what will your level of protection be with the booster shot when it's finally available
eight months after you received your first two shots with the mrna vaccines so many different
variables and still more questions than answers especially because delta is still fairly new
but in this video i'll answer them the best that i can based on the available studies that we have
now i'm going to skip over the scenario that you've not had covid or the vaccine because in
that scenario relatively speaking you have zero protection that's a dangerous gamble and with
the odds looking bleaker and bleaker depending on the underlying risk factors that you have
so let's start out with level of protection someone has from previous covid infection
but they've not had the vaccine most people after having a covid infection whether it's mild or
more severe illness they appear to have some protection against sars cov 2 for about a year
this is based on a study published in nature that looked at recovered patients there's also other
research showing that vaccinating these people significantly enhanced their immune response to
the virus and gave them strong protection against variants of concern such as the delta variant
for example researchers looked at immunity in a group of recovered adult patients one month
and six months after they were infected and some of them even had a 12-month follow-up blood draw
now the first study had 149 participants who were considered to have recovered from covid
about 10 percent were hospitalized with the covid people were excluded from the study if they had
long covid for example if they had ongoing or persistent shortness of breath chest pain
fatigue fever or loss of taste or smell now of the original 149 people 87 returned for the 6-month
follow-up and 63 came back for the 12-month follow-up 41 ended up getting at least one dose of
the mrna vaccine and that was an average 40 days before the 12-month follow-up visit so what were
the main takeaways from the study compared with six months prior those who were not vaccinated
maintained most of their plasma antibodies against the viruses receptor binding domain the rbd
also their plasma which contains antibodies had similar neutralizing activity against a
non-replicating virus that was engineered with the sars cov 2 spike protein now their memory b cells
that produce anti-rbd antibodies were only slightly lower than at the previous visit
and had evolved to produce a broader and more potent range of antibodies however their plasma
had less neutralizing activity against the variants of alpha beta iota and gamma with
the greatest loss of activity against the beta variant that was first detected in south africa
compared with unvaccinated participants those who had received at least one dose of the mrna vaccine
had higher plasma anti-rbd antibodies in a nearly 50-fold increase in neutralizing activity
so what's going on here for those who've had covid vaccination boosts the memory
antibodies that develop after infection causing there to be a more robust response
in this group neutralizing antibody levels against the variants were higher than the levels
observed against the original strain and also higher compared to fully vaccinated individuals
who did not have prior covid based on the numbers from these studies there are also more recent
studies that supported this one study in north america and the other in the uk it again showed
that a single dose of an mrna vaccine greatly enhances the immune response to covid variants
in patients who've had previous covid infection this is something called hybrid immunity so part
of the immunity coming from the immune system from previous covid infection and the other coming from
the vaccine so about the delta variant it's still relatively new so we're still learning a lot about it
a recent study in france looked at recovered patients immunity against the delta variant
specifically they looked at unvaccinated healthcare workers and they appeared to have less
protection against the delta and beta variants compared with alpha and that was about a year
after they recovered from mild covid so in this group 88 percent had neutralizing antibodies against alpha
and that's compared to 47 percent against delta but for the recovered healthcare workers who had received
one dose of either astrazeneca pfizer or moderna vaccines they had a huge increase in protective
antibodies against delta beta and alpha variants so the big takeaway here is that vaccinating
people who had previous covid will likely give them much higher protection against delta
and other variants so how long does immunity last against the delta variant from vaccination alone
so in that same study from france they also looked at those who received vaccination but did
not have previous covid infection they had high neutralizing antibody levels against the alpha
beta and delta variants 8 to 16 weeks after they received the two dose vaccine regimen in a
different study that looked at the pfizer vaccine which at this point is a study that is a pre-print
so it's not yet peer-reviewed they looked at over 45 000 people worldwide who received the
pfizer vaccine it apparently continued to show strong protection against serious illness and
hospitalization after six months but overall the protection started to wane around the six-month
mark so according to this july 28 pre-print report the study found that the overall effectiveness of
the pfizer vaccine it went from 96 to 84 so it'll be nice to see this study after it's peer reviewed
but if this turns out to be a high quality study and the results hold up
it would make sense that a booster is needed so you have this data that's in the works right now
and then there's more data that the cdc and the biden administration is basing their decision on
based on several recent studies from health systems that have been collecting data on
breakthrough infections these include the new york state health department the mayo clinic
and the cdc's reporting system for nursing homes in the united states and this is in addition to
israel's ministry of health abroad u.s surgeon general dr vivek murthy said at his briefing
we know that even highly effective vaccines become less effective over time it's now our
clinical judgment that the time to lay out a plan for covid 19 boosters is now now according to
the cdc the studies don't show any major increases in severe covid disease meaning there aren't any
major increases in hospitalizations and deaths in fully vaccinated people but the data from israel
suggests an increased risk of severe disease among those vaccinated early so the way that i
interpret that is the first group of people to receive the vaccines back in december of 2020
people like myself healthcare workers the protective antibodies likely will lose or start
to become less effective around that eight-month mark it's really all about anticipation and
being proactive and not reactive so that's why there's a plan to get these boosters in place
so starting in september the booster shots are coming for those who receive the mrna vaccines
so eight months from the time you received that vaccine that's when it's going to be
available so this does not apply to those who are immunocompromised because the third booster shot
is already available for them now and as far as level of protection in immunocompromised people
that's something i discussed in further detail in my last video which you can see here
so a lot of people are asking if we need boosters soon does that mean i'm no longer safe after just
two doses no anyone who's fully vaccinated is still very well protected from getting seriously
ill from covid the anticipation is that once you hit that eight month mark the antibodies are going
to start to wane and they won't be as effective so what about for people who've had the johnson
and johnson vaccine for now the booster shots are being advised only for the mrna vaccines but
a separate booster for that johnson and johnson vaccine is likely coming soon once more data is
available some people want to know what do federal agencies have to do to approve the booster before
september 20th in my opinion there's a good chance that the fda will grant full approval to pfizer
and moderna for the two doses probably sometime in the next few weeks and then follow that up
with an eua for the booster dose but that's just speculation on my part it's also possible that the
fda delays full approval and then give later full approval for all three at the same time
either way it's going to be the same process as when it granted eua for the mrna and the johnson
and johnson vaccines what i want to see is the data from these studies showing the numbers that
the booster is both safe and effective because without that how can we move forward with a
booster what about the flu shot when will that be given if you're also getting the booster shot
so far there aren't any guidelines on this from the cdc mainly because it hasn't been studied
i think you can expect to see a recommendation for any covid shot whether that be the booster or the
regular vaccine to be given at least a month apart from the flu shot another question is weren't they
supposed to tweak the booster shot to accommodate the new variants so as of right now the booster
shot is going to be the same as the first doses or the first two doses and not genetically tweaked to
accommodate the new strains such as delta why most likely because the booster's job will be to simply
boost the current immune system to get maximum protection against these strains until you have
a variant that is escaping the vaccines meaning lots of breakthrough infections that are causing
lots of hospitalizations and deaths there likely isn't going to be a need to genetically tweak
the current vaccine but of course this can change with time if a new variant proves to be escaping
the current vaccines so in summary what would be your level of protection against the delta variant
if you had covid your level of protection is probably mediocre but will likely fade with time
if you had just the vaccines it's probably more of the same but stronger protection if you had covid
and the vaccine your protection is likely through the roof and probably wouldn't need a booster
anytime soon but that is strictly my opinion at the time of me making this video because that
level of protection would likely be the same as someone who's not had a covid but had the