Immunity against SARS-CoV-2 Omicron variant

Two years into the pandemic, continued measures and restrictions remain
necessary to control viral circulation and prevent collapse of health care
systems. Vaccines were rapidly developed and were shown to be highly effective
at preventing severe disease and mortality. Mass immunization programs were
rolled out internationally, but vaccine coverage still strongly varies between
regions. Among the many factors driving the ongoing circulation of SARS-CoV-2,
is the surge of new variants, harboring mutations that favor transmission or
that convey an escape from immunity induced by vaccination or previous
infection with a different variant.

The SARS-CoV-2 omicron variant was recently described in Southern Africa,
associated with a rapid surge in cases, raising international concern about the
impact of novel mutations on transmission, disease severity and immunity1. The
aim of the current study is to evaluate the immunity against SARS-CoV-2 omicron
in vaccinated and unvaccinated individuals.

The key objective of the study is to characterize the immune response against
SARS-CoV-2 omicron variant.

Secondary objectives:
1. Does the clinical course of disease correlate to viral loads and the immune
response?
2. How is the CT value of the PCR correlated with the viability of the virus ?
3. How is the immune response correlated to viability of the virus?

A prospective study of health care workers with symptoms of COVID.

All participants at day 0:
• Combined nose-throat swab collected in virus transport medium: this is
diagnostics and not done for the purpose of the study
• One serum tube
• Request to fill a questionnaire and diary during disease

HCW tested SARS CoV-2 positive :
• Combined nose-throat swab collected in virus transport medium upon recovery
• One serum tube upon recovery
• One serum tube 21 days after the first swab for diagnostics (day 0)

HCW tested SARS CoV-2 negative :
• One serum tube 21 days after the first swab for diagnostics (day 0)

The second phase of the study will focus on immune responses upon vaccination,
and efficacy of vaccination in HCW with and without prior infection with SARS
CoV-2. For this aim, we will contact a maximum of 200 HCW with a confirmed SARS
CoV-2 infection and a maximum of 200 HCW without SARS CoV-2 infection for
vaccination follow up. In these HCW we will collect a blood samples prior to
their first vaccination, prior to second vaccination, 28 days post vaccination,
6 months and 1 year post vaccination. Following Erasmus MC policy, all HCW will
be urged to continue sampling and SARS CoV-2 testing once symptoms occur. In
the participating HCW these specimen will be labelled; besides a routine PCR
we will perform virus culture and sequencing.

The third phase of the study will focus on the study participants who receive a
booster vaccination. In these participants blood will be drawn prior to the
boost vaccination, 28 days after the boost and 1 year after the boost. HCW who
choose not to get a boost vaccine can continue with study phase 2.

The fourth phase involves parallel study, in which inclusions will be expanded
to non-HCW with confirmed SARS-CoV-2 omicron infection, acquired either during
travel or within the Dutch community. The reason to expand the study population
was to promote rapid collection of sufficient clinical samples to answer key
questions concerning the potential public health threat of this recently
identified variant. These results will be analyzed separately.

not applicable