Summary of findings so far – December 2021

Virus Watch is a large comprehensive household study of COVID-19 in England and Wales. Virus Watch results are proving vital in informing government planning, Public Health and NHS responses to COVID-19. This page provides an overview of the work we’ve conducted so far to help the UK and global response to the pandemic. Our research falls into four main areas: the symptoms of COVID-19, risk factors for COVID-19 including behaviours associated with COVID-19 infections as well as related to vaccination, immunity to COVID-19 and inequalities.

Inequalities
Immunity
Behaviours and Risk Factors
Symptoms

  1. Inequalities

On the 27th of July 2023, The Race Equality Foundation in partnership with UCL Virus Watch and Doctors of the World, launched a report focusing on the disproportionate impact of the COVID-19 pandemic on disempowered ethnic minority and migrant communities.

The report found that ethnic minority and migrant communities faced:

  • Increased vulnerability: Depending on the ethnic group, individuals were found to be between 5% and 88% more likely to contract the virus. This alarming disparity underscored the urgent need for targeted interventions to address the specific challenges faced by these communities, the report said.
  • Excess deaths: By April 2022, the end of community testing, Asian communities in England had over 10,500 excess deaths and Black communities almost 6,000. These are people who would likely have been alive were it not for the pandemic. Black and Asian communities had around a 23% higher risk of experiencing excess deaths and the same trend exists for other ethnic groups too.
  • Limited access to sick pay: Black, Asian, and minority ethnic workers were found to have less access to sick pay, while undocumented workers had no access to it at all. This lack of financial protection not only compromised the health and wellbeing of individuals but also perpetuated the spread of the virus within these communities.
  • Inadequate support schemes: Many Black, Asian, and minority ethnic individuals reported limited support from existing schemes. This insufficiency exacerbated the economic and social hardships faced by these communities, hindering their ability to cope with the pandemic’s impact effectively.
  • Unequal vaccination coverage: The vaccination programme failed to reach migrants and Black, Asian, and minority ethnic communities adequately, leaving them without the same level of protection as their White British counterparts. This disparity threatened to prolong the pandemic and perpetuated health disparities among different demographic groups.

The report underscored the urgent need for evidence-based policies and practices that prioritise the needs of Black, ethnic minority and migrant communities. It called for a comprehensive and inclusive approach that addresses the systemic barriers to healthcare access, ensures equitable distribution of resources, and tackles the underlying social determinants of health.

The full report can be downloaded here.

  1. Immunity

How effective is a first or second dose of COVID-19 vaccine at making antibodies against the COVID-19 virus?

In our study, a single dose of AstraZeneca or Pfizer vaccines led to high levels of antibodies against the COVID-19 virus in our participants. However, the level of antibodies varied by vaccine type, age, and other medical conditions, showing that other measures such as social distancing are still very important even after one dose of vaccine. A second dose of either vaccine resulted in high antibody levels across all groups.

How long do antibodies against the COVID-19 virus last after a second dose of vaccine, do antibody levels predict risk of infection?

We measured antibody levels in almost 9000 study participants who had received two doses of AstraZeneca or Pfizer vaccine at 3 weeks after the second dose and 20 weeks after the second dose. Antibody levels dropped at the same rate for both vaccines, but the starting level was much higher for the Pfizer vaccine. We found those with lower antibody levels were at increased risk of infection. Those vaccinated with AstraZeneca reached these lower antibody levels sooner than those vaccinated with Pfizer (96 vs 257 days) and had increased risk of breakthrough infections.  

  1. Behaviours and Risk factors

Are overcrowded living conditions a risk factor for COVID-19 infection?

People in our study living in overcrowded housing (fewer rooms than people) were more likely to have a positive PCR or antibody test for COVID-19 than people living in under-occupied housing.

What was the relative importance of going to work, shopping, public or shared transport, and other activities to non household transmission of COVID-19 in the second wave of the pandemic?

During the second wave of the pandemic going to work, using public or shared transport and shopping were all independent risk factors for catching COVID-19.  Because shopping was something most people did regularly this accounted for more transmission than going to work or public transport use, which was less common during the second wave of the pandemic.  Other non household activities were highly restricted during this period so accounted for very little transmission. The relative importance of different  activities is likely to be different since restrictions were lifted.

Where do people think they caught COVID-19?

We asked participants where they thought they had caught the virus. Place of education was most important for children, home and workplace for working age adults, and home and essential shops for those aged over 65.

How did exposure to shared airspace and close contacts in settings outside the household change from periods of intense restrictions compared to periods with no restrictions?  

When we compared weekday non household activities in March 2021 (a period of intense restrictions) and November 2021 (a period of no restrictions) we saw marked increases in frequency of use of a wide variety of settings including  public transport, eating out, going to pubs, theatres, cinemas, sports activities and parties. These settings also had high intensity of exposure to shared airspaces and, to a lesser extent, close contact.  Parties were notable for having both high exposure to shared airspace and high levels of close contact.

How much does occupation affect risk of COVID-19 infection and how do workplace exposures differ by occupation and over time?

We found the job you do makes an important difference to your risk of COVID-19 infection.  

Compared to office-based professional occupations, healthcare, teaching/education/childcare, indoor trade and process/plant (factory), and leisure and personal service occupations had higher risks of COVID-19  infection. For most of these higher risk occupations the increased risk was in the first two waves of the pandemic but teachers also stayed at higher risk during the third wave.  

How did workplace attendance and contact patterns change between occupations and over time during the COVID-19 pandemic in England?

Because the work you do affects your risk of COVID-19 we wanted to explore how working from home, workplace contacts, shared airspace and mask use varied by occupation at different times in the pandemic.  Trade occupations were most likely to attend the workplace throughout the pandemic, and office-based professional occupations least likely. Workers in leisure and service occupations became more likely to go into work from April 2021, when many workplaces reopened.  Office based occupations continued to work mainly from home even after easing of restrictions.

How does social deprivation affect public activities and non-household contacts?

Participants who lived in the most deprived areas were more likely to do activities associated with an increased risk of COVID-19 infection compared to those in less deprived areas.

How many people intended to get a COVID-19 vaccine when it became available?

We conducted an online survey of study participants in December 2020 and February 2021, asking whether people would accept a COVID-19 vaccine if offered. Only 10% of participants who answered the survey said ‘No’ or were undecided in December 2020, and more than 4 in 5 of these (86%) changed their mind or had been vaccinated by February 2021.

Do people tend to travel further outside the home after being vaccinated against COVID-19 than before vaccination?

We thought people might increase their travel soon after getting vaccinated and before they were fully protected.  Some Virus Watch participants volunteered to use a mobile phone app to track distance travelled from home.  We analysed this pre and post vaccination but found no significant increase in travel immediately after vaccination.  

  1. Symptoms of COVID-19

Which symptoms are more common in COVID-19 compared to other infections, and can we tell whether an illness is COVID-19 based on symptoms alone?

In our study, high temperature and a change in taste or smell were more likely in COVID-19 than in other infections. However, the most common symptoms of COVID-19 were general symptoms such as cough, headache, feeling tired, muscle aches, and loss of appetite. These general symptoms were also very common in other illnesses. Because the most common symptoms of COVID-19 are also often seen in other infections, it is difficult to tell apart from other infections and common illnesses based on symptoms alone.

How fast does COVID-19 spread in a household and did the ‘alpha’ variant that caused the 2020/21 winter wave spread faster than previous variants?

The average time between symptom onset in participants who reported a COVID-19 infection and participants who likely caught the infection from them was around 3 days, there did not seem to be a difference from previous variants of the virus.

How many children with COVID-19 have symptoms lasting 4 weeks or longer (‘long COVID’)?

In our study, 4.6% of children with COVID-19 reported having symptoms for 4 weeks or longer, compared to 1.7% of children overall.