Vaccine Effectivness

Comparing Vaccines

So.. just how good are the different vaccines? Note that you can’t reeeeally do a straight comparison of one vax to another because the trials measured different things with different populations and different variant mixes at different times. As a good article in The Economist says, “the gap in reported efficacy may say more about the trials than about the vaccines themselves.”

Not only that, but some trials had such low numbers of severe cases even in the placebo branch that it was really hard to draw good conclusions.

With that disclaimer, I present data below. Other sources include:

I have split off effectiveness to COVID Classic and to pre-Omicron variants (Alpha, Beta, Gamma, Delta) because the page was getting too long. There is also a page on how well non-coronavirus vaccines are against COVID. Surprisingly, many give some protection.

Efficacy against Omicron

BrandLocationAgainstWhen# dosesVE
Pfizer or AZEnglandhospitalizationomicron wave2 or 381%
Pfizer or AZEnglandhospitalizationomicron wave388%
J&JSouth Africahospitalization after 0-13 days2021-Nov-15 to 2021-Dec-20263%
J&JSouth Africahospitalization after 14-27 days2021-Nov-15 to 2021-Dec-20284%
J&JSouth Africahospitalization after 1-2 months2021-Nov-15 to 2021-Dec-20285%
ModernaCaliforniainfection at 14-90 days2021-12-06 to 2021-12-23230.4%
ModernaCaliforniainfection2021-12-06 to 2021-12-23362.5%
PfizerCaliforniaEmergency Department admission, <3 months post vaxDec 01, 2021 through Jan 11, 2022260%
PfizerCaliforniaEmergency Department admission, over 3 months post vaxDec 01, 2021 through Jan 11, 2022241%
PfizerCaliforniaEmergency Department admission, <3 months post vaxDec 01, 2021 through Jan 11, 2022378%
PfizerCaliforniaEmergency Department admission, over 3 months post vaxDec 01, 2021 through Jan 11, 2022348%
PfizerCaliforniahospital admissionDec 01, 2021 through Jan 11, 2022268%
PfizerCaliforniahospital admissionDec 01, 2021 through Jan 11, 2022289%
UK vaxes combinedUKmortality, 25 weeks laterearly 2022259%
UK vaxes combinedUKmortalityearly 2022395%
ModernaUSAinfection6 Dec 2021 to 31 Dec 2021244.0%
ModernaUSAinfection at 14-60 days6 Dec 2021 to 31 Dec 2021376.1%
ModernaUSAinfection at >60 days6 Dec 2021 to 31 Dec 2021347.4%
ModernaUSAhospitalization6 Dec 2021 to 31 Dec 20213>99%
mRNAUSAhospitalization11 Mar 2021 to 14 Jan 2022265%
mRNAUSAhospitalization11 Mar 2021 to 14 Jan 2022386%
PfizerFinlandhospitalization 14-90 days later1 Jan 2022 to 19 Feb 2022291%
PfizerFinlandhospitalization 91-180 days later1 Jan 2022 to 19 Feb 2022276%
PfizerFinlandhospitalization 14-60 days later1 Jan 2022 to 19 Feb 2022395%
mostly mRNAUSAemergency visits after 2 months26 Aug 2021 to 22 Jan 2022387%
mostly mRNAUSAhospitalization after 2 months26 Aug 2021 to 22 Jan 2022391%
mostly mRNAUSAemergency visits after 4 months26 Aug 2021 to 22 Jan 2022366%
mostly mRNAUSAhospitalization after 4 months26 Aug 2021 to 22 Jan 2022378%
PfizerHong Kongsevere disease or death31 Dec 2021 to 8 Mar 2022288.2%
CoronavacHong Kongsevere disease or death31 Dec 2021 to 8 Mar 2022274.1%
Pfizer or CoronavacHong Kongsevere disease or death31 Dec 2021 to 8 Mar 2022398.1%
Prior infection onlyQatarsymptomatic BA.223 Dec 2021 to 21 Feb 2022N/A46.1%
Pfizer (Moderna “comparable”)Qatarsymptomatic BA.2 after “several” months23 Dec 2021 to 21 Feb 20222~0%
Pfizer (Moderna “comparable”)Qatarsymptomatic BA.223 Dec 2021 to 21 Feb 2022352.2%
Pfizer (Moderna “comparable”)Qatarsymptomatic BA.223 Dec 2021 to 21 Feb 20222 plus prior infection55.1%
Pfizer (Moderna “comparable”)Qatarsymptomatic BA.223 Dec 2021 to 21 Feb 20223 plus prior infection77.3%
Pfizer (Moderna “comparable”)Qatarsevere, critical, or fatal BA.223 Dec 2021 to 21 Feb 2022any combo of vax and/or infection>70%
J&JUSAER/Urgent care visitsDec 2021 to Mar 2022124%
J&JUSAER/Urgent care visitsDec 2021 to Mar 2022254%
J&J/mRNAUSAER/Urgent care visitsDec 2021 to Mar 20221 J&J and 1 mRNA79%
mRNAUSAER/Urgent care visitsDec 2021 to Mar 2022383%
J&JUSAhospitalizationDec 2021 to Mar 2022131%
J&JUSAhospitalizationDec 2021 to Mar 2022267%
J&J/mRNAUSAhospitalizationDec 2021 to Mar 20221 J&J and 1 mRNA78%
mRNAUSAhospitalizationDec 2021 to Mar 2022390%
PfizerUSAhospitalization of 12-18 y/os1 Jul 2021 to 17 Feb 2022240%
PfizerUSA“critical COVID” of 12-18 y/os1 Jul 2021 to 17 Feb 2022279%
PfizerUSA“non-critical COVID” of 12-18 y/os1 Jul 2021 to 17 Feb 2022220%
Pediatric PfizerUSAhospitalization of 5-11 y/os1 Jul 2021 to 17 Feb 2022268%
PfizerDenmarkinfection after 14 days28 Dec 2021 to 15 Feb 2022237.0%
PfizerDenmarkinfection after 121 days28 Dec 2021 to 15 Feb 202229.8%
ModernaDenmarkinfection after 14 days28 Dec 2021 to 15 Feb 2022237.9%
ModernaDenmarkinfection after 121 days28 Dec 2021 to 15 Feb 2022213.2%
PfizerDenmarkhospitalization after 14 days28 Dec 2021 to 15 Feb 2022250.5%
PfizerDenmarkhospitalization after 121 days28 Dec 2021 to 15 Feb 2022251.6
PfizerDenmarkinfection after 14 days28 Dec 2021 to 15 Feb 2022347.9%
PfizerDenmarkinfection after 121 days28 Dec 2021 to 15 Feb 2022340.5%
ModernaDenmarkinfection after 14 days28 Dec 2021 to 15 Feb 2022347.7%
ModernaDenmarkinfection after 121 days28 Dec 2021 to 15 Feb 2022337.9%
PfizerDenmarkhospitalization after 14 days28 Dec 2021 to 15 Feb 2022388.8%
PfizerDenmarkhospitalization after 121 days28 Dec 2021 to 15 Feb 2022366.2%
ModernaDenmarkhospitalization after 14 days28 Dec 2021 to 15 Feb 2022390.2%
ModernaDenmarkhospitalization after 121 days28 Dec 2021 to 15 Feb 2022377.3%
mRNAGermanysymptomatic infection in adults25 Dec 2021 to 7 Feb 2022270%
mRNAGermanysymptomatic infection in 12-17 y/os25 Dec 2021 to 7 Feb 2022388.3%
mRNAGermanysymptomatic infection in 18-59 y/os25 Dec 2021 to 7 Feb 2022364.7%
mRNAGermanysymptomatic infection in ≥60 y/os25 Dec 2021 to 7 Feb 2022381.6%
mRNAGermanyhospitalization25 Dec 2021 to 7 Feb 2022394.4%
mRNAGermanyhospitalization in 12-17 y/os25 Dec 2021 to 7 Feb 2022390·5%
mRNAGermanyhospitalization in 18-59 y/os25 Dec 2021 to 7 Feb 2022389.9%
mRNAGermanyhospitalization in ≥60 y/os25 Dec 2021 to 7 Feb 2022395.9%
mRNAGermanysevere illness25 Dec 2021 to 7 Feb 2022397.5%
mRNAGermanysevere illness in 18-59 y/os25 Dec 2021 to 7 Feb 2022396·2%
mRNAGermanysevere illness in ≥60 y/os 25 Dec 2021 to 7 Feb 2022397·7%
mRNAUSA PROTECTinfection, 5-11 y/oJul 2021 to Feb 2022231%
mRNAUSA PROTECTinfection, 12-18 y/o, 14-149 daysJul 2021 to Feb 2022259%
mRNAUSA PROTECTinfection, 12-18 y/o, ≥150 days daysJul 2021 to Feb 2022262%
PfizerUSAinfection, 5-11 y/o1 Jul 2021 to 17 Feb 2022268%
PfizerUSAinfection, 12-18 y/o, 2-22 weeks1 Jul 2021 to 17 Feb 2022242%
PfizerUSAinfection, 12-18 y/o, 23-44 weeks1 Jul 2021 to 17 Feb 2022236%
PfizerUSAhospitalization, 12-18 y/o1 Jul 2021 to 17 Feb 2022220%
PfizerUSAlife support or death, 12-18 y/o1 Jul 2021 to 17 Feb 2022279%
PfizerIsraelinfection3 Jan 2022 to 18 Feb 2022445%
PfizerIsraelsymptomatic infection (relative to 3 doses)3 Jan 2022 to 18 Feb 2022455%
PfizerIsraelhospitalization (relative to 3 doses)3 Jan 2022 to 18 Feb 2022468%
PfizerIsraelsevere disease (relative to 3 doses)3 Jan 2022 to 18 Feb 2022462%
PfizerIsraeldeath (relative to 3 doses)3 Jan 2022 to 18 Feb 2022474%
PfizerFinlandhospitalization after 14-90 days1 Jan 2022 to 19 Feb 2022291%
PfizerFinlandhospitalization after 14-60 days1 Jan 2022 to 19 Feb 2022395%
PfizerFinlandhospitalization after 91-180 days1 Jan 2022 to 19 Feb 2022276%
mRNADenmarkinfection after 14-30 days, over 60 y/o21 Dec 2021 to 31 Jan 2022239.9%
mRNADenmarkinfection after >120 days, over 60 y/o21 Dec 2021 to 31 Jan 202224.7%
mRNADenmarkinfection after 14-30 days, over 60 y/o21 Dec 2021 to 31 Jan 2022357.6%
mRNADenmarkinfection after >120 days, over 60 y/o21 Dec 2021 to 31 Jan 2022352.8%
mRNADenmarkinfection after 14-30 days, 12-59 y/o21 Dec 2021 to 31 Jan 2022239.8%
mRNADenmarkinfection after >120 days, 12-59 y/o21 Dec 2021 to 31 Jan 2022213.2%
mRNADenmarkinfection after 14-30 days, 12-59 y/o21 Dec 2021 to 31 Jan 2022355.2%
mRNADenmarkinfection after >120 days, 12-59 y/o21 Dec 2021 to 31 Jan 2022349.9%
mRNADenmarkhospitalization after 14-30 days, over 60 y/o21 Dec 2021 to 31 Jan 2022394.4%
mRNADenmarkhospitalization >120 days, over 60 y/o21 Dec 2021 to 31 Jan 2022377.3%
mRNADenmarkhospitalization after 14-30 days, 12-59 y/o21 Dec 2021 to 31 Jan 2022262.4%
mRNADenmarkhospitalization after >120 days, 12-59 y/o21 Dec 2021 to 31 Jan 2022265.9%
mRNADenmarkhospitalization after 14-30 days, 12-59 y/o21 Dec 2021 to 31 Jan 2022389.3%
mRNADenmarkhospitalization after >120 days, 12-59 y/o21 Dec 2021 to 31 Jan 2022333.3%
PfizerCaliforniahospital admission after >9 months1 Dec 2021 to 6 Feb 2022241%
PfizerCaliforniaER admission after >9 months1 Dec 2021 to 6 Feb 2022231%
PfizerCaliforniahospital admission after <3 months1 Dec 2021 to 6 Feb 2022385%
PfizerCaliforniahospital admission after >3 months1 Dec 2021 to 6 Feb 2022355%
PfizerCaliforniaER admission after <3 months1 Dec 2021 to 6 Feb 2022377%
PfizerCaliforniaER admission after >3 months1 Dec 2021 to 6 Feb 2022353%
mRNACalifornia prisonsinfection24 Dec 2021 to 14 Apr 2022214.9%
mRNACalifornia prisonsinfection24 Dec 2021 to 14 Apr 2022343.2%
mRNACalifornia prisonsbreakthrough infection, after pre-Delta infection24 Dec 2021 to 14 Apr 2022247.8%
mRNACalifornia prisonsbreakthrough infection, after pre-Delta infection24 Dec 2021 to 14 Apr 2022361.3%
mRNACalifornia prisonsbreakthrough infection, after Delta infection24 Dec 2021 to 14 Apr 2022273.1%
mRNACalifornia prisonsbreakthrough infection, after Delta infection24 Dec 2021 to 14 Apr 2022386.8%
PfizerIsraelinfection, kids 5-1123 Nov 2021 to 7 Jan 2022117%
PfizerIsraelinfection, kids 5-1123 Nov 2021 to 7 Jan 2022251%
PfizerIsraelsymptomatic infection, kids 5-1123 Nov 2021 to 7 Jan 2022118%
PfizerIsraelsymptomatic infection, kids 5-1123 Nov 2021 to 7 Jan 2022248%
ArcturusVietnamsevere cases“Delta and Omicron”295.3%
ArcturusVietnaminfection“Delta and Omicron”255.0%
PfizerSouthern CaliforniaBA.1 ER admission27 Dec 2021 to 4 Jun 2022229%
PfizerSouthern CaliforniaBA.1 hospitalization27 Dec 2021 to 4 Jun 2022240%
PfizerSouthern CaliforniaBA.1 ER admission, <3 months after vax27 Dec 2021 to 4 Jun 2022374%
PfizerSouthern CaliforniaBA.1 ER admission, >3 months after vax27 Dec 2021 to 4 Jun 2022365%
PfizerSouthern CaliforniaBA.1 hospitalization <3 months post-vax27 Dec 2021 to 4 Jun 2022380%
PfizerSouthern CaliforniaBA.1 hospitalization >3 months post-vax27 Dec 2021 to 4 Jun 2022376%
PfizerSouthern CaliforniaBA.2 ER admission27 Dec 2021 to 4 Jun 2022216%
PfizerSouthern CaliforniaBA.2 hospitalization27 Dec 2021 to 4 Jun 2022256%
PfizerSouthern CaliforniaBA.2 ER admission <3 months post-vax27 Dec 2021 to 4 Jun 2022359%
PfizerSouthern CaliforniaBA.2 ER admission >3 months post-vax27 Dec 2021 to 4 Jun 202235%
PfizerSouthern CaliforniaBA.2 hospitalization <3 months post-vax27 Dec 2021 to 4 Jun 2022374%
PfizerSouthern CaliforniaBA.2 hospitalization >3 months post-vax27 Dec 2021 to 4 Jun 2022370%
whatever, mostly mRNAUSA(BA.1) hospitalization <120 days post-vax“BA.1 period”392%
whatever, mostly mRNAUSA(BA.1) hospitalization >=120 days post-vax“BA.1 period”385%
whatever, mostly mRNAUSA(BA.2) hospitalization <120 days post-vaxBA.2 period369%
whatever, mostly mRNAUSA(BA.2) hospitalization >=120 days post-vaxBA.2 period352%
whatever, mostly mRNAUSA(BA.2/BA.2.12.1) hospitalization >=120 days post vax for people over 50BA.2/BA.2.12.1 period355%
whatever, mostly mRNAUSA(BA.2/BA.2.12.1) hospitalization >=7 days post vax for people over 50BA.2/BA.2.12.1 period480%
whatever, mostly mRNAUSA(BA.1) hospitalization >=150 days post-vaxBA.1 period261%
whatever, mostly mRNAUSA(BA.2/BA.2.12.1) hospitalization >=150 days post-vaxBA.2/BA.2.12.1 period224%
whatever, mostly mRNAUSA(BA.2/BA.2.12.1) ER visit >=120 days post-vaxBA.2/BA.2.12.1 period332%
whatever, mostly mRNAUSA(BA.2/BA.2.12.1) ER visit >7 days post-vaxBA.2/BA.2.12.1 period466%
PfizerSingaporePCR or rapid test confirmed infection, 5-11 y/os21 Jan 2022, through 8 Apr 2022113.6%
PfizerSingaporePCR confirmed infection, 5-11 y/os21 Jan 2022, through 8 Apr 2022124.3%
PfizerSingaporehospitalization, 5-11 y/os21 Jan 2022, through 8 Apr 2022142.3%
PfizerSingaporePCR or rapid test confirmed infection, 5-11 y/os21 Jan 2022, through 8 Apr 2022236.8%
PfizerSingaporePCR confirmed infection, 5-11 y/os21 Jan 2022, through 8 Apr 2022265.3%
PfizerSingaporeinfection, 5-11 y/os21 Jan 2022, through 8 Apr 2022282.7%
PfizerHong Kongmild or moderate disease in 20-59 y/os31 Dec through 16 Mar 2022235·1%
CoronaVacHong Kongmild or moderate disease in 20-59 y/os31 Dec through 16 Mar 2022225·1%
PfizerHong Kongmild or moderate disease in 20-59 y/os31 Dec through 16 Mar 2022373·5%
CoronaVacHong Kongmild or moderate disease in 20-59 y/os31 Dec through 16 Mar 2022351·0%
PfizerHong Kongsevere disease in over 20-59 y/os31 Dec through 16 Mar 2022296·3%
CoronaVacHong Kongsevere disease in over 20-59 y/os31 Dec through 16 Mar 2022291·7%
PfizerHong Kongsevere disease in 60-69 y/os31 Dec through 16 Mar 2022291.1%
CoronaVacHong Kongsevere disease in 60-69 y/os31 Dec through 16 Mar 2022279·3%
PfizerHong Kongsevere disease in over 80 y/os31 Dec through 16 Mar 2022286·9%
CoronaVacHong Kongsevere disease in over 80 y/os31 Dec through 16 Mar 2022258·2%
PfizerHong Kongdeath in over 80 y/os31 Dec through 16 Mar 2022290·3%
CoronaVacHong Kongdeath in over 80 y/os31 Dec through 16 Mar 2022263·0%
PfizerHong Kongsevere/fatal disease, all ages 31 Dec through 16 Mar 2022398·6% – 99·0%
CoronaVacHong Kongsevere/fatal disease, all ages 31 Dec through 16 Mar 2022395·4% – 98·8%
variousPortugalhospitalization, BA.225 Apr to 10 Jun 2022393%
variousPortugalhospitalization, BA.525 Apr to 10 Jun 2022377%
variousPortugaldeath, BA.225 Apr to 10 Jun 2022394%
variousPortugaldeath, BA.525 Apr to 10 Jun 2022388%
Moderna or PfizerSingaporeinfection NB: fast waning27 Dec 2021 to 10 Mar 2022331.7% to 41.3%
Moderna or PfizerSingaporesevere disease NB: minimal waning27 Dec 2021 to 10 Mar 2022387.4%
Sinovac or SinopharmSingaporesevere disease27 Dec 2021 to 10 Mar 2022369.6%.
PfizerSouth Africahospitalization during BA.1/BA.2 period at 3-4 months15 Nov 2021, to 28 Feb 2022256.3%
PfizerSouth Africahospitalization
BA.4/BA.5 period at 3-4 months
15 Apr to 24 Jun 2022247.4%
PfizerSouth Africahospitalization
BA.1/BA.2 period at 3-4 months
15 Nov 2021, to 28 Feb 2022350.0%
PfizerSouth Africahospitalization
BA.4/BA.5 time period at 3-4 months
15 Apr to 24 Jun 2022346.8%

Dose Interval

What is the optimal interval?

It is my understanding that in most vaccines, you want a fairly long interval between dose 1 and dose 2. The immune system needs some time to learn and train from the first dose.

Why then, are were the recommended intervals so short initially? Because the vaccine makers were in a real hurry. They did the absolute shortest interval that they thought they could get away with.

There have been a lot of people who have had longer intervals since then. It was a bit of a calculated gamble to do so before the data was in, but it was apparently a pretty safe bet, since all other vaccines did better with a longer dose interval.

Since then, there have been a few studies.

  • This study of Pfizer in people over 80 found that they generated 2.5x as many antibodies with a 12-week interval than with a 4-week interval.
  • This study of AZ found that antibodies were higher with a 12-week dose interval than an interval shorter than six weeks.
  • This study of AZ found that antibodies were higher the longer the dosing interval was. They studied up to 44 weeks.
  • This study of Pfizer found that neutralizing antibodies were higher for a long dosing interval (6-14 weeks) compared to a short interval (3-4 weeks).
  • This study of Pfizer found that a 16-week interval was better than a 4 week interval.
  • This study of Pfizer and Moderna found that antibody levels were higher in people who had a 6 to 7 week interval than in people who had a 3 to 4 week interval.

There also have been literally millions of people who have had a longer interval. For example, in BC, most of the 2.3M people who have gotten a second dose (as of 18 July 2021) have had a dose interval longer than 7 weeks. (Mine was ten weeks; my partner’s eleven.) The UK has also had a long dose interval.

Waning Effectiveness

There have been a bunch of studies documenting a significant decrease in effectiveness against infection over time. There is a small drop against hospitalization and death, but not nearly as large.

It is not entirely surprising that the vaccines are less effective against infection but still very good against severe disease. Antibodies are the first line of defence, and they are kind of designed to go away when they are not needed, but to get called back in force when there is an infection. It takes a few days for a new antibody army to get raised, however, which gives time for infection to take hold.


The first Pfizer clinical trials said that the vaccine efficacy after only one dose was 92%, but this re-examination of the clinical data gives much better numbers:

I believe I saw another paper which said that the efficacy declined quite a bit after five weeks, but I would have to dig a bit harder to find that the paper.


This preprint did a meta-analysis of a bunch of waning studies. They found that vaccine effectiveness dropped a lot between 1 and 6 months after the second dose:

againstageschange
asymptomatic infectionall-18.5%
asymptomatic infectionolder-19.9%
symptomatic infectionall-25.4%
symptomatic infectionolder-32.0%
severe diseaseall-8.0%
severe diseaseolder-9.7%

This study from BC and Quebec showed a lot less waning — more like 10% than 20-30% — for long dose intervals than for short dose intervals:

This image has an empty alt attribute; its file name is Screen-Shot-2021-11-22-at-2.16.56-PM-1024x625.png

This preprint reports waning of two doses of AZ in Scotland and Brazil. The vaccine effectiveness against severe disease was:

2-3 weeks14-15 weeks18-19 weeks
Scotland83·7%75·9%63·7%
Brazil86·4%59·7%42·2%

Note that there are lot of papers on waning effectiveness, I just got bored writing them all down.

Boosters

This publication from Public Health England says that the vaccine effectiveness was 93.1% for those over 50 with AZ+AZ+Pfizer and 94.0% for Pfizer+Pfizer+Pfizer.


This big study which looked at Pfizer, Moderna, AZ, J&J, Novavax, CureVac, and Valneva as boosters for AZ/AZ or Pfizer/Pfizer found that (broadly speaking), the more mRNA, the better. (See my 2 Dec 2021 analysis for more detail and nuance.)


<there have been a bunch more booster studies, they all show that a booster increases effectiveness against infection, at least in the short term… I need to add them in…>


This preprint says that the J&J boosters (i.e. second dose) in South Africa does well. Its effectiveness against infection was:

  • 63% effective 0-13 days after the second dose
  • 84% effective 14-27 days days after the second dose
  • 85% effective 1-2 months days after the second dose

This preprint says that for Pfizer doses in the USA:

  • effectiveness against infection dropped from 85% during the first month after dose2 to 49% >= 7 months after dose2;
  • effectiveness against hospitalization after dose2 was 90% and did not wane significantly;
  • effectiveness against infection was 88% after dose3;
  • effectiveness against hospitalization was 97% after dose3;
  • relative effectiveness (vs. unvaccinated) against infection after dose3 was 75%;
  • relative effectiveness (vs. unvaccinated) against hospitalization after dose3 was 70%.