Seroprevalence of COVID-19 in hairdressers and catering staff (COco-study)

On February 27th, 2020, the first Dutch patient was diagnosed with COVID-19, a
SARSCoV-2 infection. The virus spread quickly and since than almost 6000
patients died from the effects of this infection, which is expected just the
tip of the tip of the iceberg. At the end of April the first Dutch serological
studies (PIENTER 3, Sanquin) were released. These studies reported an incidence
rate of 3-4% among the Dutch population who had experienced the virus. The
province of Noord-Brabant is the most severely affected Dutch province. It is
expected that in the region West-Brabant about 5-10% of the population produced
antibodies against COVID-19

Since the start of the outbreak in the Netherlands, various measures have been
taken to reduce the spread in the population and to protect vulnerable people
in particular. As a result, the reproduction number (R0) has fallen below 1
since the end of March, which means that the virus is extinguishing in the
Netherlands. This means that the taken measures in place can be relaxed.

For example hairdressers and catering staff are allowed to return to work.
However, little is known about the effect of easing these measures on Dutch
society. The medical scientific literature focuses in particular on COVID-19 in
critically ill patients admitted to hospital. Much remains unknown about
asymptomatic infections and transmission in the general population and specific
populations outside the hospital.

In the COco study, we investigate the consequences of resuming work on the risk
of COVID-19 in hairdressers and catering staff, in the West Brabant region.
Because the province of Noord-Brabant is the seat of the Dutch pandemic, this
is a unique region to perform this study. The results of the COco study can be
used for policy on this virus throughout the Netherlands.
In this study, GGD West-Brabant enters into a chain collaboration with
Microvida (Breda), Amphi / University Nijmegen and Sanquin, and professional
associations of hairdressers and catering staff are involved in the research.

Primary research goal
- Evaluate whether resuming activities of hairdressers and catering staff
results in a significantly higher percentage that produces antibodies against
SARS-CoV-2 after 3 months.

Secondary research goals
- Identifying determinants (age, gender, function, co-morbidity, lifestyle,
etc.) for antibody production against SARS-CoV-2.

Evaluate whether:
- there is a difference in antibody production between hairdressers and
catering staff after resuming their activities.
- there is a difference in antibody production between personnel working in
contact professions after resuming their activities and the general population
of West Brabant, as tested by Sanquin.
- there is a difference in antibody production between staff working in contact
professions after resuming their activities and hospital staff / professional
football players.
- there are seasonal influences on the antibody production against SARS-CoV-2
in hairdressers and catering staff.

- Evaluate what percentage of patients afflicted with COVID-19 as measured by
PCR produce detectable antibodies to SARS-CoV-2.
- Get a picture of the duration that antibodies (expected) remain measurable in
the blood after initial detection.

The COco study is a prospective study. After inclusion, bloodsamples (3,5 ml)
are taken from study participants to determine the seroprevalence at baseline
(t0). In addition, baseline data is collected through a survey (age, gender,
migration background, education level (socioeconomic status), lifestyle,
function, complaints in the past three months, previously tested for
SARS-CoV-2, measures taken by the employer to prevent spread of the virus,
etc.). During the study period, participants keep a record of whether they have
complaints that are appropriate for COVID-19, how much they have worked and, if
applicable, with which protective measures. They also record whether they show
risk behavior outside their work. If participants have complaints appropriate
to COVID-19, they will be tested for SARS-CoV-2 by PCR from a throat and
nasopharyngeal swab.

After 3 months (t1), another 3,5 ml of blood is taken to determine antibodies.
This seroprevalence and sero incidence has been compared with the general
population of West Brabant in collaboration with Sanquin, and with the hospital
staff and professional football players in our region in collaboration with
Prof. Kluytmans. Similar studies are performed in parallel in these
populations, using the same serological assays, allowing reliable comparison.

Given the measures taken in our region and the period in which the study will
start (summer period), we expect that after three months, about 10% of the West
Brabant population will still have made antibodies against SARS-CoV-2. We
consider it clinically relevant if this prevalence is 50% higher in our study
population, i.e. 15%. With an alpha of 0.05 and power of 80%, we need to
include 398 people in our study, 199 per group. We expect 10% failure. For
catering staff we assume a dropout rate of 20%.

Hairdressers 10% dropout: 199 * 1.10 = 219 people
Catering industry 20% dropout: 199 * 1.20 = 239 people

In addition, we expect that 8% of the people in contact professions already
have antibodies, so they are not included in the incidence calculation.

Hairdressers: 219 / 0.92 = 238
Catering industry: 239 / 0.92 = 260
Total sample: 498

A third measurement will be carried out in December 2020 (t3). The purpose of
this measurement is to measure the seasonal influences on antibody production
against SARS-CoV-2. Because we expect that the antibody production in the West
Brabant population has increased further with this measurement, a population of
498 people is sufficient, even with an increase in participants who drop out.
If there is an indication of seasonal influence, a fourth measurement will
follow in April 2021 (t3) to measure the antibody production again at the end
of the "virus season". This is the case if the sero incident ratio (t1-> t2
versus t0-> t1) of our population is above 1.2.

Employees from the hairdressing and catering industry who participate in the
COco study have a negligible risk and experience a minimal burden. In a period
of maximum 10 months, a maximum of 5 hours of their time is requested. A blood
sample of 3,5 ml is drawn up to 4 times. When a follow-up subject in the
self-report indicates that he has symptoms suggesting a COVID-19 infection, a
nasopharyngeal / throat swab is performed.

At the time of inclusion, a baseline questionnaire is completed that takes a
maximum of 15 minutes from participants. In the following weeks, a short
questionnaire (completion time: 5 minutes) is administered weekly, in which the
experienced symptoms are also recorded.
Subjects do not experience any direct benefit from the study. Individual test
results are made available to each subject during the study; results of the
study will be summarized upon completion of the study.