Evidence Check - Epidemiology and transmission

Community transmission and hospital infection, stages of pandemic, immunity, vaccination.

Children and COVID-19 outcomes

Added: 29 Sep 2021

Evidence in brief on children and COVID-19 outcomes
  • Early in the COVID-19 pandemic in Australia, very few children were admitted to hospital, with only 44 hospitalisations nationally between February and September 2020
  • The clinical course for most children positive for SARS-CoV-2 was mild.
  • Multisystem inflammatory syndrome in children, or paediatric inflammatory multisystem syndrome, is a childhood disease that is temporally associated with COVID-19. While most children survive, the long-term outcomes are currently unknown.
  • With the implementation of vaccination in adults and the emergence of the Delta strain, children are increasingly infected.
  • While evidence on transmission from children is limited, a recent New England Journal of Medicine letter found efficient transmission of SARS-CoV-2 from school-age children and adolescents to household members led to the hospitalisation of adults with secondary cases of COVID-19.
  • There are calls to offer vaccination to adolescents and young adults. In Australia, both Pfizer and Moderna have been approved for use in people aged 12 years and older.

COVID-19 vaccines and fertility

Added: 17 Sep 2021

Evidence in brief on COVID-19 vaccines and fertility
  • The Royal Australian and New Zealand College of Obstetricians and Gynaecologists and the Australian Technical Advisory Group on Immunisation recommend that - pregnant women are routinely offered Pfizer mRNA vaccine (Cominarty) at any stage of pregnancy - pregnant women are encouraged to discuss the decision in relation to the timing of vaccination with their health professional - women who are trying to become pregnant do not need to delay vaccination or avoid becoming pregnant after vaccination.
  • There is no evidence to suggest COVID-19 vaccines affect fertility.
  • Observational studies have found that - COVID-19 vaccines did not affect patients' performance or ovarian reserve in couples undergoing IVF - in men, there are no significant decreases in any sperm parameters, compared with people who weren’t vaccinated.

Ocular transmission

Added: 27 Aug 2021

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is transmitted person-to-person through close contact, mainly through respiratory droplets. According to the World Health Organization infection may occur where respiratory droplets containing virus reach the mouth, nose or eyes of a susceptible person.
There is some evidence of SARS-CoV-2 detection in ocular swab samples however the prevalence is low (0-17%). Evidence is limited and conflicting about whether SARS-CoV-2 can spread through the mucous membranes of the eye.
  • While ocular transmission has been proposed as a transmission route for SARS-CoV-2, via the nasolacrimal duct into the respiratory tract, there is no evidence of definite ocular transmission of SARS-CoV-2.
  • SARS-CoV-2 can cause ocular symptoms, in particular conjunctivitis, however prevalence is low (between 0-35%).3-5, 7, 8 There is a potential but unconfirmed risk of transmission from conjunctiva.

Steroid use post COVID-19 vaccination

Added: 27 Aug 2021

Does the use of steroids post COVID-19 vaccination impact vaccine efficacy?
  • Phase 3 trials for Pfizer/BioNTech, Moderna and Oxford/AstraZeneca excluded individuals receiving corticosteroids or immunosuppressant medication at specific doses and time periods. No subgroup analysis for those who were on these medications at eligible doses was provided.
  • Two peer-reviewed articles from the American Society of Pain and Neuroscience and Spine Intervention Society’s Patient Safety Committee summarise the literature on steroid medications and their impact on vaccine safety and efficacy.
  • Limited prospective cohort studies (small sample sizes, one preprint) of individuals who had received mRNA vaccines found that use of steroids associated with reduced antibody response.
  • The Australian Rheumatology Association advises that for people on stable chronic glucocorticoid therapy, modification of dose is not necessary. For people on higher doses who are planning to taper, the advice is to consider deferring vaccination until the dose is lower (e.g. <10mg/day), depending on the individual disease, comorbidities, likely trajectory of glucocorticoid therapy and an estimate of the risk of COVID-19.
  • The US Centres for Disease Control and Prevention advises that COVID-19 vaccines may be administered without regard to timing of corticosteroid treatment, including topical or intraarticular, bursal, or tendon injection.
  • Versus Arthritis (UK) advises that people who are on steroids can have COVID-19 vaccination, however, may need to follow guidance on shielding and social distancing after receiving the vaccination.

Delta variant

Added: 19 Aug 2021

Evidence in brief on the Delta variant
  • The Delta variant has been estimated to be more than twice as transmissible as the originalstrain of SAR-CoV-2. First recognised in India, it has now spread to over 100 countries.
  • The current NSW outbreak is due to the Delta variant.
  • The risk of hospitalisation from COVID-19 is almost doubled for patients infected with Delta (Sgene positive cases), compared with people infected with the Alpha variant. Both the Oxford–AstraZeneca and Pfizer–BioNTech COVID-19 vaccines were effective in reducing the risk ofSARS-CoV-2 infection and COVID-19 hospitalisation in people with Delta.

Archive Facial hair, masks and COVID-19 transmission

Added: 25 Jun 2021

Optimal use of respirator face masks such as N95 or filtering facepiece masks depends on a tight seal with the wearer's skin.
  • Tight-fitting respirator face masks such as N95 or filtering facepiece masks are considered the reference standard respiratory protective equipment for healthcare workers working in aerosol-generating procedures. Optimal use of these depends on a tight seal with the wearer's skin.
  • The purpose of fit testing is to ensure that the selected make, model and size of a respirator issued to a wearer forms an adequate seal around the wearer’s face providing protection. The Critical Intelligence Unit has published an evidence check on respirator fit testing.
  • The Clinical Excellence Commission recommends that healthcare workers must not have any facial hair present when commencing fit testing and when using a respirator. International organisations consistently describe facial hair as a contraindication to the workplace use of tight-fitting respirator masks.
  • Many organisations, for example the US Centers for Disease Control and Prevention, provide graphics depicting facial hairstyles and filtering facepiece respirators.
  • A requirement to be clean shaven to facilitate the effective wearing of respiratory protective equipment may indirectly discriminate against certain groups.
  • The COVID-19 pandemic has seen a shift away from beards towards clean shaves in response to personal protective equipment guidance.

Archive Respirator fit testing

Added: 29 Oct 2020
Updated: 25 Jun 2021

What is the effectiveness of fit testing (both qualitative and quantitative methods) and fit checking for testing the protection of a respirator and what are the factors influencing the outcomes of fit testing?
What are the differences in outcomes between the qualitative and quantitative fit testing methods?
  • The purpose of fit testing is to ensure that the selected make, model and size of a respirator issued to a wearer forms an adequate seal around the wearer’s face and provides the intended level of protection.(1) The Australian New Zealand Standard AS/NZS1715:2009 Selection, Use and Maintenance of Respiratory Protective Equipment states that fit testing can be performed using qualitative or quantitative methods. • Qualitative fit testing is a pass/fail test method that uses the wearer’s sense of taste or smell to detect leakage into the respirator facepiece. This type of fit testing is usually used for half-mask respirators. • Quantitative fit testing measures the amount of leakage into the facepiece using a generated aerosol, ambient aerosol or controlled negative pressure. This type of fit testing connects a respirator to a machine using a probe attached to the respirator.
  • Fit checking (user-seal check) describes the process that health workers perform each time a respirator is donned to check that a good facial seal is achieved, i.e. the respirator is sealed over the bridge of the nose and mouth and there are no gaps between the respirator and the face.

Archive COVID-19 vaccine and elective surgery

Added: 20 May 2021

What is the evidence on COVID-19 vaccination before elective surgery, including any recommendations regarding timing of vaccination?
  • Expert consensus from international professional societies generally recommend vaccinating patients against SARS-CoV-2 before elective surgery, as this may reduce the risk of COVID-19 complications and transmission of the virus during procedures.
  • Recommendations on the timing for preoperative COVID-19 vaccination is variable, ranging from a few days to weeks due to the unknown vaccine immunogenicity.
  • COVIDSurg, a modelling study based on data from almost 60,000 patients internationally, found that fewer people need to be vaccinated to prevent one death in surgical patients compared with the general population.
  • COVIDSurg estimated that globally, prioritising all surgical patients for preoperative vaccination ahead of the general population is projected to prevent an additional 58,687 COVID-19-related deaths in one year.
  • The timing for surgery, and potential for vaccine prioritisation, would need to take into account the context of the surgery and disease prevalence. For example, in some settings it may not be appropriate to prioritise surgical patients over vulnerable groups such as the elderly, and advice may vary for different surgeries.
  • The Royal College of Surgeons of England recommends that emergency surgery take place irrespective of COVID-19 immunisation status.

Daily Evidence Digest

Rapid evidence checks are based on a simplified review method and may not be entirely exhaustive, but aim to provide a balanced assessment of what is already known about a specific problem or issue. This brief has not been peer-reviewed and should not be a substitute for individual clinical judgement, nor is it an endorsed position of NSW Health.

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