Research press release


Scientific Reports

COVID-19: Compliance to household mixing restrictions in England decreased with each lockdown

イングランドでは、最初のロックダウンで複数世帯の人々が集まる行動が著しく減り、2度目のロックダウンでも比較的少なかったが、3度目のロックダウンでは増えていたことを報告する論文が、Scientific Reports で発表される。この論文には、3度目のロックダウンの際に複数世帯の人々が集まる行動が増えた2021年2月中旬が、イングランド全土で重症急性呼吸器症候群コロナウイルス2(SARS-CoV-2)ワクチン接種が拡大した時期と一致していたという観察結果が示されている。

今回の研究で、Ed Manleyたちは、データが研究目的で使用されることに同意した100万人以上の匿名ユーザーの携帯電話データを使用した。このデータは、EU一般データ保護規則(GDPR)に準拠している。Manleyたちは、イングランドでのパンデミック発生の8週間前の世帯訪問数の平均値から算出したベースライン値とパンデミック期間中の世帯訪問数を比較した。その結果、最初のロックダウン(2020年3月~)の際に複数世帯の人々が集まる行動が最も大きく減少した(54.4%減)が、禁止措置が解除されると、年末まで徐々に増加していったことが判明した。また、2度目のロックダウン(2020年11月~)の減少幅と3度目のロックダウンの最初の月(2021年1月)の減少幅は、それぞれ15.28%と26.22%だった。複数世帯の人々が集まる行動には地域差があり、一部の都市域(ロンドン、マンチェスター、ケンブリッジなど)では増加していた。



Household mixing significantly decreased in the first lockdown in England and remained relatively low in the second lockdown, but increased during the third lockdown, reports a study published in Scientific Reports. The authors observed that the increase in household mixing by mid-February 2021 during the third lockdown coincided with the wider COVID-19 vaccine rollout across England.

Professor Ed Manley and colleagues used GDPR-compliant mobile phone data from over one million anonymous users who provided consent for their data to be used for research purposes. The authors compared household mixing across the pandemic to baseline levels, calculated from average household visits eight weeks before the pandemic began in England. The authors observed the largest decrease of 54.4% in household mixing during the first lockdown (starting in March 2020) which gradually increased across 2020 as restrictions were lifted. The authors also observed household mixing reduced by 15.28% in the second lockdown (starting in November 2020) and the initial month of the third lockdown by 26.22% (January 2021). Household mixing varied across regions, with some urbanised areas including London, Manchester and Cambridge associated with increased household mixing.

The significant increase in household mixing by mid-February 2021 rose above baseline levels by between 1.4% and 23.3% during the third lockdown, despite national restrictions remaining in place. The increase in household mixing coincided with the announcement that the most vulnerable had been vaccinated, and the wider rollout of the vaccination programme across England. The authors propose this significant increase in household mixing during the third lockdown may reflect the widespread perception of safety from vaccinations. The authors also suggest that “lockdown fatigue” contributed to higher levels of household mixing in later lockdowns.

The authors conclude their study of mobile phone data may provide a useful privacy-preserving tool in helping assess the effectiveness of COVID-19 public health policies at local and national scales. The authors did not predict any associations between potential future restrictions or booster vaccinations and household mixing.

doi: 10.1038/s41598-021-02092-7


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