[updated on August 5, 2021] Delta variant has been developing rapidly these previous weeks and
has infected 15 provinces in China*. Up to 7pm on 5th August, 2021 5 high-risk
and 183 medium-risk areas have been identified in China mainland
according to the National Health Commission's report.
Dr. Warren Ho, Internal Medicine physician at ParkwayHealth,
answers five questions about Delta variant and Covid-19 vaccine:
1. Why is Delta more powerful and how will situation develop?
Primarily, Delta is more powerful because it is more
contagious. It also has a shorter incubation period. It does not
appear to be more severe per se. It is the strain behind recent waves in
many regions. Development of situation requires further monitoring.
2. Why did some patients get vaccinated and still get infected？
Vaccines significantly lower the risk of all levels of
infection - asymptomatic, mild and severe. They do not eliminate the risk
of infection with delta or previous strains, but they are key in slowing the
spread, reducing morbidity and protecting the vulnerable around you.
3. How effective is vaccine against the Delta mutant strain?
A study in the New England Journal of Medicine showed that
two shots of the Pfizer or Astra-Zeneca vaccines were almost as effective
against the delta strain vs. the alpha (original) strain.
As concerning as the recent delta outbreaks in China are,
the Chinese epidemiology expert Zhong Nanshan noted that early evidence from
the Guangzhou delta outbreak suggests that the Chinese vaccines also offer
similar relative protection against delta.
4. Is it necessary to have the third booster injection? Can we
mix different vaccine brand?
Guidance on booster injections is still being considered.
Pfizer is studying a booster injection of its vaccine after 6-12 months based
on its data from Israel. However, policies regarding booster vaccinations are
naturally still evolving. There is no theoretical problem with using a
different vaccine as a booster, but many combinations have not been studied
yet.
5. Under which physical conditions will vaccination not be recommended？
In general, poorly controlled chronic diseases (eg,
diabetes, hypertension, autoimmune diseases) and acute illnesses should be
addressed before any elective treatment. However, this is true whether or
not one wants to get vaccinated, and it rarely delays vaccination for long.
*Data from National Health Commission on August 5, 2021
Answers from Dr. Warren Ho, Internal Medicine physician at ParkwayHealth
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