Dr. Naor Bar-Zeev, who has been in the forefront of educating the public about COVID-19, graciously agree to answer a few questions about COVID-19.
Q: In Israel, they have already
vaccinated 1 million people. Why the delay here? When and where will the
vaccine be available?
A: The development of a safe and
efficacious vaccine against COVID-19 was a remarkable success. Operation Warp
Speed has been very focused on the scientific development of the vaccine, and
very large taxpayer investments made this possible. The challenge now is the
large-scale production and equitable and efficient distribution of the vaccine
to the population.
This is an enormous task. Public
health specialists have been spelling out the complexities of this gargantuan
task for many months now. Most countries are finding this challenging. Israel
has seen early success in roll-out. This in part is because of the modest
population and geographic size of the country, and because Israel’s kupot cholim, the HMOs, are well
designed to provide universal health care to all the population. The population
is enumerated, every citizen is enrolled in a kupa, there are national identity numbers, and there are universal
electronic registers. Israel has also been flexible enough to make use of any
residual doses, so that these don’t go to waste. Israel’s population thus far
has been enthusiastic in receiving the vaccine.
The United States is incomparably
larger, more diverse, and geographically vast. Its health system does not
provide universal care, and there are layers of governance: federal, state, and
local. Early in the pandemic, we saw blame shifting – sometimes partisan – on
resource (like ventilators and personal protective equipment) availability
between the state and federal governments. The U.S. is now in a difficult
transition of power. States are starting to deploy their distribution plans.
Most states have already submitted their plans for review and made these
available to citizens for comment.
Roll-out will be phased, as many
readers here will know – with healthcare workers, older adults, and essential
workers prioritized, as well as persons with other medical conditions that put
them at risk of severe COVID-19 disease. How one defines a healthcare worker or
an essential worker will lead to debate. How do we identify and reach persons
with co-existing medical conditions? How do we engage with communities that may
feel hesitant to receive vaccination? All these are important issues that state
and local governments are dealing with right at this moment. Once systems for
communication, delivery, and supply ramp up, we hope there will be smooth and
efficient availability of vaccination for the community. For more information,
it is worth checking marylandvax.com and the Maryland State Health Department
websites.
Q: How long after receiving the
vaccine can one shed the mask and social distancing?
A: There is a conceptual difference
between infection (when a pathogen enters the body) and disease. We know that
the SARS-CoV-2 virus, in many cases, can cause infection without disease; that
is, it can be asymptomatic. We also know that it can spread from
asymptomatically-infected persons. Now we know from well-conducted large trials
that the COVID-19 vaccines that have received Emergency Use Authorization (EUA)
by the Food and Drug Administration (FDA) protect to a high degree against
COVID-19 disease. However, at this stage it is not known whether this current
first generation of COVID-19 vaccines will reduce asymptomatic infection of
SARS-CoV-2 or transmission. There is some evidence from animal studies that
they might, but it is unclear how well they will do so in humans at population
level. For technical reasons, we are unlikely to know this from the Phase 3
trials.
Some data from other vaccine
platforms (not yet licensed in the U.S.) suggest that impact on transmission
may be rather modest. For this reason, it remains important to continue using
masks and maintain distancing. It also means we have to make a really strong
effort to ensure that everyone who is at risk of severe COVID-19 disease gets
vaccinated to protect them from disease. This should be prioritized at this
stage over the idea of vaccinating everyone to achieve herd protection. We do
not yet have sufficient evidence that vaccines will induce herd protection,
though of course we hope they will. But we need further studies to determine
this.
Q: Are you worried about the new
strain of COVID in England? Will the vaccine be effective against it?
A: Every person is a unique
individual and yet we are one species; we are all human. In much the same way,
SARS-CoV-2, although it is a specific species of virus, like all life, will
diversify into families and clades. This is normal and expected. Nowadays, we
have powerful genetic sequencing technologies that can identify single
base-pair difference (smaller than a single gene) between individuals, so we
will discover many such differences. The question is not whether they will
occur. The question is whether they will matter.
They can matter in three ways: 1) They
can be more infectious, 2) they can be more pathogenic (cause worse disease),
or 3) they can become vaccine escape mutants, which means they will be
different enough from the vaccination-induced immunity to evade detection by
the human immune system. At this stage, there is indirect evidence that some of
the emergent strains are more transmissible. There is no evidence they make you
sicker, and the degree of change in them makes it unlikely that the vaccine won’t
work against them. Over time this situation could change. Luckily, the mRNA
vaccine platform is very amenable to tiny tweaks to keep it effective against
new emergent escape-mutations. It might be the case that, in the future, such
adjustments to the mRNA code might be needed. But we are far from that scenario
currently. The more successful we are at rolling out the vaccines, and if it
does turn out to reduce transmission, then this will also slow the emergence of
new strains.
Q: Rare adverse events have been
reported in the media, should we worry about them? How well will they be
reported?
A: Despite the slow initial roll-out
of the vaccine, it has already been given to millions of people around the
world. The speed of this roll-out, together with the fact that it is being
given mostly to older adults, many of whom have other medical conditions, means
that events will occur after vaccination, and these will be quickly reported in
social media. It will be important to be able to distinguish events that occur
after vaccine but are not caused by vaccination, from those that are caused by
the vaccine.
I emphasize, temporal association
(B occurring after A) is necessary but not sufficient to establish causation.
(Just because B followed A doesn’t prove that A caused B.) For this reason, it
is important that we continue post-licensure surveillance, and report all
suspected adverse events following vaccination. The United States has a very
robust system for such reporting. We should not dismiss concerns as spurious
without evaluation, and at the same time we should not jump to presume
causation for every event that occurs. We need to be thorough, diligent,
systematic, and humble. We need to work hard. There are examples of past vaccines
that were withdrawn after licensure and roll out. I think this is unlikely to
occur here, but it is not impossible.
As ever, the risks of rare adverse
events must be balanced against the risk of not being vaccinated. Thinking only
about risk from vaccination is only half the logic. The other half is what is
the risk of not vaccinating? This balance of risks will vary for different
groups and in different settings and over time. But for now, there is no doubt
that the risk of COVID-19, even for younger persons, is far greater than the
risk of rare events that may be due to vaccination.
Naor Bar-Zeev is a pediatric infectious diseases
physician and statistical epidemiologist, associate professor of international
health and vaccine sciences, and is deputy director of the
International Vaccine Access Center at Johns Hopkins Bloomberg School of Public
Health.
