SARSLIVA 2.0: Dense saliva sampling for studying SARS-CoV-2 transmission dynamics - a household study

In mitigating the SARS-CoV-2 pandemic, governments have to weigh the public
health benefits of interventions such as closing schools, restaurants and
theaters against the significant social and economic disruption they impose.
After opening schools and public life and restarting the economy, close
monitoring of the spread of the virus is a critical tool for successfully
detecting the virus and the spread of SARS-CoV-2 in the population.

It has recently been shown that the detection of the virus in saliva by
molecular diagnostics is at least as sensitive as the most commonly used method
for viral detection in nasopharyngeal (NP) swabs. Saliva samples are a very
attractive way for large-scale monitoring of SARS-CoV-2 spread, especially
because it offers the possibility of self-sampling in the home situation.

The current situation in the Netherlands is: 84.6% of people over 12 years old
have been fully vaccinated and 54.9% of people over 18 years old have received
a booster vaccination. The current dominant circulating variant is the Omicron
variant of SARS-CoV-2. Omicron shows higher transmissivity compared to previous
variants and is less sensitive to neutralizing antibodies, causing high rates
of infections in fully vaccinated individuals - even those who received a
booster vaccination, although the clinical signs appear mild compared to
previous variants.

Therefore, the current dynamics of SARS-CoV-2 transmission (for example, in
households) may be very different from the results described in the SARSLIVA
study and this would have implications for public health strategies, such as
quarantine and isolation policies, school closures and other infection control.
measures.

Follow up
A substantial proportion of SARS-CoV-2 infected people experience ongoing
symptoms more than 6 months after the acute phase, such as fatigue, dyspnea and
joint pain . These subacute and long-term symptoms are recognized as *Long-
COVID* or *Post-acute Sequelae of SARS-CoV-2 (PASC)*. A large Systematic
Review including 250.000 children and adults from 57 studies previous infected
by SARS-CoV-2, noted a prevalence of PASC of 54.0 % (31.0%-67.0%) 6 or more
months after SARS-CoV-2 infection. Data on the longer-term health consequences
of SARS-CoV-2 infections is still limited, especially after mild or
asymptomatic SARS-CoV-2 infection. In most studies, follow-up is restricted to
6 months after infection.

Moreover, data regarding development of long-term complaints after infection
with the Omicron variant of SARS-CoV-2 in individuals vaccinated against
SARS-CoV-2, and the impact of Post-acute sequelae on quality of life is scarce.
In the present follow-up study, we want to investigate this by following
participants during 12 months using standardized questionnaires on 2 time
points for post-acute symptoms and quality of life.

Substudy on reinfections
Reinfections with SARS-CoV-2 occur frequently due to declining immunity after
previous infection and/or vaccination and the emergence of new virus variants
that partially circumvent existing immunity. Therefore, there remains a risk of
new corona waves in the current phase of the Covid-19 pandemic, especially
during the winter season. A better understanding of the longevity of protective
immunity and the risk of reinfections, including their impact on individual
health, allows improved preparedness and can inform optimally targeted measures
to limit the impact on individuals and society. For this reason, this project
mainly focuses on research into identifying risk factors for reinfections,
including the role of waning immunity, and on understanding how these
reinfections affect our health and daily functioning in the short and long
term.

primary objectives:
SARSLIA 2.0:
1. To study SARS-CoV-2 transmission dynamics within households using saliva,
with home self-sampling, storage and transport to the laboratory.
2. To study the emergence of SARS-CoV-2 in saliva from asymptomatic or
pre-symptomatic household contacts, duration of the presence of SARS-CoV-2 in
saliva, and the changes in viral load over time in relation to disease severity.

Follow up:
3. To study the post-acute sequelae of SARS-CoV-2 infection (PASC), such as
quality of life and clinical symptoms 6 and 12 months after SARSl-CoV-2
infection.

Reinfection substudy:
4. to determine the incidence rate of reinfections with SARS-CoV-2.
5. To investigate risk factors (demographic, clinical, virological,
immunological) for SARS-CoV-2 reinfections.
6. To understand which factors determine the longevity and breadth of
protective SARS-CoV-2-specific humoral immunity.
7. To determine the health impact of SARS-CoV-2 reinfections or their sequelae.



secondary objectives:
SARSLIVA 2.0
1. To study the difference in SARS-CoV-2 transmission dynamics within
households during the alpha and delta wave when adults and children in the
Netherlands were largely unvaccinated, compared to the transmission dynamics
within households during the current Omicron wave of the COVID-19 pandemic with
the majority of the population being vaccinated
2. The emergence of IgA, IgM and IgG anti-SARS-CoV-2 specific antibodies in
saliva and serum.

Reinfection study:
3. To determine the incidence rate of (co-)infections with influenza viruses
and RSV

This will be a prospective cohort study of patients with COVID-19 and their
household contacts

The burden of participating in this study is minimal. Blood collection will
take place only twice and will be performed by a finger prick, which may cause
transient discomfort and only rarely infection. Saliva collection holds no
risk. Saliva sampling will be repeated in total 10 times for SARS-CoV-2
positive subjects and household members. Participants will also be required to
complete a total of 10 questionnaires, which is expected to take 10x5 minutes
maximum per person. The index patient or his/her parents/legal representatives
will be asked to fill in a baseline questionnaire, this questionaire will also
take 5 minutes per person to fill in.

Household members that were infected by SARS-CoV-2 (confirmed by antigen- or
PCR-test) during the previous 8 weeks will be required to complete 1 online
questionnaire, which is expected to take one time 10 minutes.

No additional visits to the hospital are required. Study staff will drop off
required sampling material and picked up saliva samples at participant homes.
It is important to note that study participants should still follow the advice
from the municipal health services regarding testing for SARS-CoV-2

At the end of the study, the study physician will inform participants on the
results from the saliva samples, which are not analysed directly.

Follow up:
The follow-up questionnaires at 6 and 12 months after inclusion are expected to
take 2x10 minutes per person.

Substudy SARS-CoV-2 reinfections
The burden of participating in this study is minimal. Blood collection will
take place four times. On M3 and M9, blood will be self-collected at home by
finger prick. At M0 and M6, blood will be collected by venepuncture in adults
and children >= 16 years old. In children <12 years old, blood will be collected
by finger prick. In children 12-15 years old, blood will preferably be
collected by venepuncture (with EMLA), or by finger prick in case of
participants preference. This may cause transient mild discomfort and only
rarely infection. Oropharyngeal swab collection holds no risk. Oropharyngeal
sampling can cause mild discomfort. Participants will also be asked to complete
at least 4 questionnaires, which is expected to take 20 minutes maximum per
person per questionnaire. In case of symptoms, participants will fill in an
additional questionnaire, which is expected to take 20 minutes maximum per
person. The 2 home visits (Month0 and Month6) are estimated to take 5 minutes
per person in the household. Study staff will drop off required sampling
material and perform the venous blood collections.
Participants participating in the extension of the substudy, will be followed
up for additional 6 months. During these months, participants will continue
collecting NP/OP swabs. One additional blood collection and questionnaire is
implemeted at april 2024.