Covid-19 Medical Risk Assessment

COVID-AGE

Last updated 8 July 2020

SUMMARY – HOW TO ASSESS A WORKER’S VULNERABILITY

What is ‘vulnerability’?

The risk that someone will die from Covid-19 infection is a combination of the risk that they will get the infection, and the risk that, once infected, they will develop serious illness and die (‘vulnerability’).

The risk that someone will get the infection through work can be reduced through control measures that minimise workplace exposure and through use of personal protective equipment. If the risk that someone will get the infection through work remains higher than their risk of becoming infected outside work, then, for the individual worker, their personal vulnerability becomes important.

What is Covid-age?

Covid-age is a simple, easy to use tool that helps assess an individual’s vulnerability to Covid-19. It is based on published evidence for the main risk factors. Age was chosen as the basis for the tool because the evidence shows age is the greatest risk factor for death from Covid-19; for example, in comparison with a healthy person aged 20, a healthy person aged 60 has more than 30 times the risk of dying if they contract Covid-19.

Covid-age summarises vulnerability for combinations of risk factors including age, sex and ethnicity and various health problems. It works by “translating” the risk associated with each risk factor into years which are added to (or subtracted from) an individual’s actual age.  This then gives a single overall measure of vulnerability. It can be used in people with no underlying medical conditions or multiple medical conditions. One measure combines all of an individual’s risk factors with their actual age.

Covid-age does not provide an exact measure, so when it is used to calculate vulnerability from medical conditions, and particularly multiple medical conditions, clinical judgement must also be used by a suitably qualified health professional. It is intended as part of an occupational health assessment of fitness for work. It is not intended for use in clinical treatment pathways.

How do I use Covid-age?

To calculate Covid-age, take the person’s actual age and add any additional factors from Table 1 below. For example:

  1. A healthy white woman, aged 40, has a Covid-age of (40-8) = 32 years
  2. A white man aged 45, BMI 36 with severe asthma, has a Covid-age of (45+5+4) = 54 years.
  3. An Asian woman aged 50 with Type 2 diabetes has a Covid-age of (50-8+4+9) = 55 years.

The Covid-age scale is based on the vulnerability of healthy white men. So, for example:

Someone with a Covid-age of 25 has the same vulnerability as a healthy white man aged 25.

Someone with a Covid-age of 55 has the same vulnerability as a healthy white man aged 55.

The 45-year-old man in example 2 above has the same vulnerability as a healthy white man aged 54 years; in example 3 the 50 year old Asian woman has the same vulnerability as a healthy white man aged 55 years.

Employers will want to know what to do with ‘Covid-age’. One simple approach is to put workers into different vulnerability groups based on their Covid-age. They can then be given different roles or protection depending on the nature of their work, their vulnerability group, and the expected level of Covid-19 in the local population.

We have included a table at the bottom of this webpage to illustrate these four vulnerability groups given the current prevalence of Covid-19 in the UK. A pdf of this summary can be downloaded here Covid-age; assessing a worker’s vulnerability and a questionnaire for management can be downloaded here Covid-age Individual Vulnerability Questionnaire

AIM

This website provides information about personal vulnerability to Covid-19 according to age, sex, ethnicity and comorbidities.  Its purpose is to assist health professionals in the UK who are asked to advise about patients’ medical fitness for work that may entail exposure to coronavirus. It is not intended for, or suitable for use as a clinical practice guideline.

CONTEXT

In managing occupational risks of Covid-19, employers must control exposure to the virus so far as is reasonably practicable, taking into account the possibility that some workers will be more vulnerable than others should they contract the disease.  Guidance on the overall approach to risk management can be found at Returning_to_the_workplace_COVID-19_toolkit_FINAL and specifically for healthcare workers at Risk-Reduction-Framework-for-NHS-staff-at-risk-of-COVID-19-infection-12-05-20 and SOM_RTW_guide_health_professionals_COVID-19_FINAL.

Strategies may include changes to the way in which work is carried out, use of barriers and personal protective equipment (PPE), and in some cases, exclusion or redeployment of individuals who are more vulnerable.

The need for selective exclusion/redeployment of vulnerable workers will depend on the likelihood of their contracting Covid-19 through their work (which will vary according to the job and the prevalence of infection in the local community), and on the extent of their personal vulnerability to severe illness should they get the disease.

ASSESSMENT OF VULNERABILITY AND COVID-AGE

The best evidence on vulnerability to Covid-19 comes from epidemiological research.  From analysis of epidemiological data for the UK, the contributions to vulnerability from sex, ethnicity and some of the most common comorbidities among people of working age have been summarised in terms of their equivalence to added years of age (see Table 1 below).  This allows calculation of a person’s “Covid-age” – a simple summary measure indicating the age of a healthy white male with equivalent vulnerability . We start with the individual’s biological age, then add/subtract the age adjustments from the table. For example:

A healthy white woman, age 40, has a Covid-age of (40-8) = 32 years

A white man age 45, BMI 36, severe asthma, has a Covid-age of (45+5+4) = 54 years.

An Asian woman age 50, Type 2 diabetes HbA1c>58, has a Covid-age of (50-8+5+10) = 57 years.

To give the measure context, we also provide estimates of case fatality rates in healthy white men by age. (see Table 2 below). As relevant new evidence becomes available, evidence-based assessment of vulnerability will be updated and refined, with extension to other categories of comorbidity where that becomes possible. 

The background evidence and methods can be found here: Methods at 200629

and the original paper was placed on the medRxiv pre-print server:  2020.05.21.20108969v1.full

We are aware that a number of calculators and copies of the table below are being used by various occupational health providers. We are keen to share this tool with everyone and hope it will be widely used, but are concerned that copies may become rapidly out of date as the table below is amended, and there is a risk that calculators will be used without clinical judgement. We therefore recommend that only the current table below is used when determining Covid-age.

Table 1.  Vulnerability from risk factors expressed as equivalence to added years of age

Risk factor Relative risk Equivalent added years of age Robustness of risk estimate
Female sex 0.5 -8 Robust
Ethnicity
Asian or Asian British 1.5 4 Moderately robust
Black 1.7 6 Moderately robust
Mixed 1.6 5 Provisional
Other non-white 1.3 3 Provisional
Body mass index (Kg/m2)
30-34.9 1.4 4 Provisional
35-39.9 1.6 5 Provisional
≥40 2.4 10 Provisional
Asthma
Mild (no requirement for oral corticosteroids in past year) 1.1 1 Moderately robust
Severe (requiring oral corticosteroids in past year) 1.4 4 Moderately robust
Diabetes
Type 1
HbA1c≤58 mmol/mol in past year 2.0 8 Moderately robust
HbA1c>58 mmol/mol in past year 2.7 11 Moderately robust
HbA1c unknown 3.3 13 Moderately robust
Type 2 and other
HbA1c≤58 mmol/mol in past year 1.5 4 Moderately robust
HbA1c>58 mmol/mol in past year 2.0 8 Moderately robust
HbA1c unknown 2.3 9 Moderately robust
Heart failure 2.2 9 Provisional
Other chronic heart disease 1.3 3 Provisional
Cerebrovascular disease 2.2 9 Provisional
Chronic respiratory disease (excluding asthma) 1.9 7 Moderately robust
Chronic kidney disease* 1.7 6 Moderately robust
Non-haematological cancer
Diagnosed <1 year ago 1.6 5 Provisional
Diagnosed 1-4.9 years ago 1.2 2 Provisional
Diagnosed ≥5 years ago 1 0 Provisional
Haematological malignancy
Diagnosed <1 year ago 3.5 14 Provisional
Diagnosed 1-4.9 years ago 3.1 13 Provisional
Diagnosed ≥5 years ago 1.9 7 Provisional
Liver disease 1.6 5 Provisional
Chronic neurological disease other than stroke or dementia** 2.5 10 Provisional
Organ transplant 4.3 16 Provisional
Spleen diseases† 1.4 4 Provisional
Rheumatoid/lupus/psoriasis 1.2 2 Provisional
Other immunosuppressive condition‡ 1.8 7 Provisional

*Glomerular filtration rate <60mL/min/1.73m2, as estimated from the most recent serum creatinine measurement.

**Includes motor neurone disease, myasthenia gravis, multiple sclerosis, Parkinson’s disease, cerebral palsy, quadriplegia, hemiplegia, malignant primary brain tumour and progressive cerebellar disease.

†Includes splenectomy, or spleen dysfunction (e.g. from sickle cell disease).

‡Includes HIV, conditions inducing permanent immunodeficiency (ever diagnosed), aplastic anaemia, and temporary immunodeficiency recorded within the past year.

 Table 2. Relative risks of mortality from Covid-19 and estimated case fatality rates in healthy white males by age

Age (years) Estimated risk relative to that at age 47 years (healthy white males) Estimated case-fatality rate per 1000 in cases of Covid-19 infection (healthy white males)
20 0.1 0.2
25 0.1 0.3
30 0.2 0.4
35 0.3 0.7
40 0.5 1.1
45 0.8 1.7
47 1.0 2.0
50 1.3 2.6
52 1.6 3.1
54 1.9 3.8
56 2.3 4.5
58 2.7 5.4
60 3.2 6.5
62 3.9 7.7
64 4.6 9.3
66 5.6 11
68 6.7 13
70 8.0 16
72 9.6 19
74 11.5 23
76 13.7 27
78 16.4 33
80 19.7 39

QUALITATIVE GUIDANCE

Meanwhile, qualitative guidance on predicted vulnerability from comorbidities that have not yet been studied epidemiologically is provided in risk tables that were compiled by clinical experts soon after Covid-19 emerged (see separate pages listed at the bottom of this page). Although compiled by expert clinicians, this qualitative guidance is inevitably much less reliable than that based on epidemiological data. It may change substantially as further information becomes available; we have kept these tables for the time being, although it is clear that some of the guidance is no longer in line with emerging evidence, particularly for some conditions where evidence suggests the vulnerability is significantly lower. When compiled, it stratified vulnerability into ‘very high’, ‘high’, ‘moderate’ and ‘low’ in accordance to the likely effect of Covid-19 on the individual. Clinical judgement will be required when considering how this relates to Covid-age.

VULNERABILITY LEVELS

Stratification of vulnerability should ideally be based on the defined risk. In the case of mortality from Covid-19 infection it would have to relate numbers of deaths to numbers infected. It would then be up to those making policy decisions to decide on appropriate risk levels for various activities. Occupational health specialists would rightly be advising policy-makers but should not themselves dictate appropriate risk levels. Any ultimate decision on risk levels would also be informed by personal choice and expediency (including the necessity of that individual undertaking a specific task). Currently there is no clear denominator, so it is not possible to define an exact level of risk, only relative risk. 

In the absence of any clear policy decisions on risk levels, we can only interpret likely appropriate vulnerability levels. Currently guidance has set two levels of vulnerability, ‘clinically extremely vulnerable (CEV)’ who have been sent shielding letters, and ‘clinically vulnerable (CV)’ who have underlying medical conditions considered to make them more vulnerable or who are over age 70.  As over 2m shielding letters have been sent out, around 4% of the population are considered to be in the CEV group, and around 40% are in the CV group. 

Determining a ‘Covid-age’ level that would represent the 96th centile would be challenging. For men, around 4.4% of the ppulation are aged 77 and above. Taking into account the likely Covid-age distribution for men around that age, it is likely that around 4% of men have a Covid-age of 85 and above, so it would be appropriate to set a point of ‘very high vulnerability at between 80 and 85 if it were to include at least 4% of the population. PHE defined age 70 as ‘CV’ and noted that around 40% of the population would be in the CV group, so it would also be appropriate to consider those with a Covid-age of 50 and above to be at moderate vulnerability and those of Covid-age of 70 and above to be high vulnerability. Clinical judgement should be used to decide which group is appropriate for any individual. It is important to recognise that these are arbitrary values, not based on absolute risk. It is hoped that these will be redefined once risk levels are defined by Government, through PHE or HSE.
Vulnerability level Definition Workplace considerations
Very High

Covid-age 80 to 85 and above

High risk of death if infection occurs.

Those who must take great care when they leave the security of their own home.

Ideally work from home.

If attending work, the risk should not be significantly greater than the risk within their own home.

Ensure low likelihood of anyone breaching social distancing. Ensure they can maintain good personal hygiene with low likelihood of contacting contaminated objects and surfaces.

High

Covid-age around 70 to 85

High risk of becoming hospitalised and seriously ill if infection occurs.

Those can leave their home to go shopping or for a walk in the park, and associate freely with other members of their household.

OK to attend work if the risk of doing so is no greater than the risk of shopping in the local supermarket, or social distancing in the streets, parks and countryside.

Keep the risk in the workplace as low as reasonably practicable by redeployment or controls including PPE.

Clinical work, care work and working closely with others (such as teaching, sharing a vehicle, using public transport) may be possible provided controls (e.g. screens, PPE) are effective in managing the risk.

Some individuals in essential roles may be asked to accept a higher risk and agree to do so where this can be justified.

Moderate

Covid-age around 50 to 70

Those who are much less likely to develop severe disease if infection occurs A moderately increased risk of infection may be accepted where there are no reasonably practicable means of reducing it further.

Includes clinical work with higher hazard and risk levels, or roles where physical control or restraint is required, or where additional risk has to be accepted and can be justified.

Low

Covid-age below around 50

Those who are very unlikely to develop serious disease if infection occurs Increased risk of infection may be accepted where there are no reasonably practicable means of reducing it further.
Pregnancy No current evidence of significantly increased risk to mother or baby unless mother has significant medical problems Current advice is to minimise the risk to pregnant women, while allowing them to choose whether to attend work and what role to undertake at work. Risk should be reduced as far as reasonably practicable.

Advised to avoid roles where a degree of risk cannot be avoided, such as clinical work, care work and working closely with others

 

PROJECT PARTICIPANTS

The work has been undertaken by the Joint Occupational Health COVID-19 Group:

Principal Authors:

Prof David Coggon, Southampton, Prof Peter Croft, Keele, Prof Paul Cullinan, Imperial College, Dr Tony Williams, Working Fit Ltd

Strategy Group:

Prof Ewan MacDonald, Glasgow, Prof Raymond Agius, Manchester, Prof Mike Pearson, Liverpool, Dr Anne de Bono, Faculty of Occupational Medicine, Dr Will Ponsonby, Society of Occupational Medicine, Dr Blandina Blackburn, NHS Health at Work Network, Dr Alastair Leckie, NHS Lothian

Working Group for Tables:

Dr Jacqui Bollman, Dr Pam Collins, Dr Andrew Dickson, Dr Emma McCollum, Dr Kerry McNeil, Dr Pam Mellors, Dr Peter Noone, Dr Chris Valentine, Dr Eugene Waclawski, Dr Tony Williams

Project Manager:

Dr Tony Williams, Working Fit Ltd

covid19@workingfit.com