BNT162b2 COVID-19 vaccination uptake, safety, effectiveness and waning in children and young people aged 12–17 years in Scotland

September 2022: Research published in The Lancet Regional Health Europe looks at the uptake, safety, and effectiveness over time of the Pfizer-BioNTech COVID-19 vaccine for people aged 12-17 in Scotland.

Summary in plain English

The Pfizer-BioNTech vaccine has been shown in clinical trials to be safe and effective for 12-17 year olds and younger children. The UK started to roll out vaccines for young people in the second half of 2021.

Young people in Scotland could access their first COVID-19 vaccine from:

• 6 August 2021: All 16-17 year olds, and some 12-15 year olds in priority groups
• 20 September 2021: All 12-15 year olds
• 19 March 2022: All 5-11 year olds.

Some children and young people might have received their first COVID-19 vaccine before the dates stated above. This includes children who live with adults in a high-risk group; are clinically vulnerable to COVID-19; or were less than three months from their 18^th birthday.

Why did we carry out this study?

Early research on COVID-19 showed that symptoms were generally milder in children. However, some groups are at higher risk of serious illness which may need hospital treatment.

Analysing vaccine benefits, and potential risks, nationally can help people make evidence-based decisions about getting a vaccine. This includes policymakers, healthcare staff, young people and their care-givers.

We wanted to understand:

• Uptake: how many people in Scotland aged 12-17 have received a COVID-19 vaccine
• Safety: adding to available evidence on vaccine safety in 12–17-year-olds
• Effectiveness: how well COVID-19 vaccines protect people against COVID-19 symptoms
• Waning: how long COVID-19 vaccine protection lasts.

What data did we use?

To carry out this study, we used data from the EAVE II dataset, as well as data held by Public Health Scotland. EAVE II covers 99% of the Scottish population. As of 1 March 2022, this includes 350,300 people under 18 years old.

Find out more about EAVE II

We looked at effectiveness data from the start of the main vaccine rollout, on 6 August 2021, until 1 March 2022. There were two main variants of coronavirus (SARS-CoV-2) during this time. The ‘Delta period’, when the Delta variant was most common in Scotland, ranged from the start of the study until 19 December 2021. The ‘Omicron period’ lasted from 20 December 2021 until the end of the study.

For vaccine safety, we included everyone aged 12-17 vaccinated between 8 December 2020 and 30 April 2022. We followed up on hospital and GP records for this group from 1 September 2020 until 30 April 2022.

What did we find?

How many people aged 12-17 had COVID-19 vaccines in Scotland?

By 1 March 2022, the following percentages of young people had received vaccines:

• 16-17 year olds: 75.9% had first dose, 49.0% had second dose
• 12-15 year olds: 64.5% had first dose, 37.2% had second dose.

This includes 6,865 young people vaccinated before the general rollout on 6 August 2021. More young people have been vaccinated since 1 March 2022.

How safe are the vaccines for young people?

Twenty-nine potential side effects were chosen to include in this study. These were based on:

• outcomes recommended for monitoring by the World Health Organization
• the Safety Platform for Emergency vACcines (SPEAC)
• side effects previously monitored for influenza vaccines
• discussions with experts and clinicians.

The 29 side effects of interest were then grouped into 17 health outcomes, based on similarities. We then looked at hospital admissions for these 17 health outcomes.

For 13 of the 17 health outcomes we studied, fewer than five young people were admitted to hospital with the health outcome following either a first or second dose COVID-19 vaccine.

We analysed hospital data for the remaining four health outcomes, after receiving a COVID-19 vaccine:

• type 1 diabetes
• vasculitis and inflammatory conditions
• seizures
• chronic fatigue.

We did not find an increased risk of any of these four health outcomes in young people who received a COVID-19 vaccine.

We also studied GP data for cases of myocarditis and pericarditis, but did not find any increased risk.

How effective are vaccines in preventing COVID-19 symptoms?

In the 2-5 weeks after receiving two doses of a COVID-19 vaccine, vaccine effectiveness against symptomatic COVID-19 cases was:

• 16-17 year olds: 95.6% in the Delta and 65.5% in the Omicron period
• 12-15 year olds: 100.0% in the Delta and 81.2% in the Omicron period.  

The vaccine effectiveness of a single dose of a COVID-19 vaccine was 30-50% lower than having two doses, for both groups in both the Delta and Omicron period.

The protective effect against symptomatic disease began to drop five weeks after people had their first or second dose.

Why is this research important?

This is the first study in the world to look at the uptake, safety, effectiveness and waning protection against COVID-19 symptoms of two vaccine doses, for an entire national population of young people. The effectiveness results cover the period when both Delta and Omicron variants were common.

It shows that having two doses of Pfizer-BioNTech vaccine gives people aged 12-17 good protection against symptomatic infection in the Delta and Omicron periods. There was no link between vaccination and any of the potential health outcomes studied. However, vaccine protection against symptomatic infection is short-lived.

In adults, waning effectiveness against symptomatic COVID-19 has also been seen. However, protection against serious illness has been shown to last much longer.

Note

This plain English summary was written by our Patient and Public Involvement Lead Lana Woolford, with the support and feedback of the EAVE II Public Advisory Group (PAG) and researchers.