Are mandatory influenza vaccinations to healthcare employees effective?

Question

There is a new law about come into effect in Finland that would, amongst other things, mandate all healthcare employees have yearly vaccinations. Here is a link to the webpage of the new law (in Finnish).

There is also a citizens' initiative (Finnish web-page) aiming to stop the new law from being enforced.

The initiative argues against the effectiveness of these mandatory vaccinations:

Esimerkiksi influenssarokotteen vaikuttavuudesta on saatavilla luotettavaa ja puolueetonta tietoa. Cochrane-katsauksen mukaan henkilökunnan influenssarokotteen suojavaikutuksesta laboratoriotestauksin varmistettuun influenssaan, keuhkokuumeeseen tai kuolleisuuteen 60-vuotiailla ja vanhemmilla hoidettavilla ei ollut näyttöä (3). Kattavaa laumaimmuniteettia on myös erittäin vaikea saavuttaa henkilökunnan rokotuksilla, eikä siitä todennäköisesti ole edes hyötyä potilaille (4). Viime vuosina on ollut myös epäilyjä siitä, että influenssarokotteen teho laskee rokotusten myötä vuosi vuodelta (5). Influenssan torjunnassa tärkeintä on edelleen hyvän hygienian merkitys (4).

And my translation into English:

There is credible and unbiased information regarding the effectiveness of influenza vaccinations. According to Cochrane review there is no evidence between influenza vaccination of (healthcare) personnel to laboratory-tested influenza, pneumonia or mortality of 60 years old and older patients (3). Comprehensive herd-immunity is also very hard to achieve with (healthcare) personnel vaccinations and it won't probably even provide any benefit to patients (4). There has been suspicions in recent years that the efficiency of influenza vaccinations is decreasing year by year (5). The most important aspect on defending from influenza is still good hygiene (4).

The new law would require personnel vaccinations for measles, chicken pox, influenza and pertussis (pertussis only for personnel treating under one year olds). The initiative proposes that part as a whole to be removed.

The corresponding sources to back up these claims are:

(3) Thomas, Jefferson & Lasserson 2016. Influenza vaccination for healthcare workers who care for people aged 60 or older living in long-term care institutions. Cochrane

(4) Dolan ym. 2012. Vaccination of health care workers to protect patients at increased risk for acute respiratory disease. Emerg Infect Dis. 2012 Aug;18(8):1225-34.

(5) Friedman 2015. The flu vaccine may have a strange problem that US scientists can't fix.

Are influenza vaccinations to healthcare personnel effective? Is there a scientific consensus about the matter?

I believe the new law aims to protect the patients better by vaccinating the employees (correct me if I'm wrong). Thus the effectiveness should be scrutinized on the ability to better the patients' safety. The citizens' initiative argues that this goes against the individual autonomy of the workers i.e. educated professionals should have the last say on their own vaccinations.

Answer 1

My answer is going to be wishy washy, so if it reads that way... it's not because I'm misexpressing myself.

As user "anonymized" pointed out, it's not too clear what the premise of the proposed law is: to lessen the chance that healthcare personnel misses work because of flu, or that they protect their patients by not spreading the flu to them. Or maybe both. So, with the risk of making the answer a bit long, let's try to address both.

On the first issue, whether flu vaccines protect the direct recipient, the CDC is firmly on the side of flu vaccination, even though the flu vaccines apparently has a substantial variability in effectiveness, ranged between 10% and 60% in a 2017 news piece in Science. The argument for seems to be that that's [far] better than nothing. The arguments against are more complicated involving potential long-term effects of the vaccine on the flu itself and/or receiver's immunity, which seem harder to weigh. These arguments are raised by reputable scientists in reputable venues, so it's not a case of crackpottery like the opposition to some other vaccines. E.g., one study cited by Friedman's opinion piece says:

In vaccinated subjects with no evidence of prior season vaccination, significant protection (62% [95% CI, 17%–82%]) against community-acquired influenza was demonstrated. Substantially lower effectiveness was noted among subjects who were vaccinated in both the current and prior season. There was no evidence that vaccination prevented household transmission once influenza was introduced; adults were at particular risk despite vaccination.

Some of the authors of this study work for the CDC Influenza Division, by the way.

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On the issue of healthcare workers' vaccination protecting their patients from flu, the two reviews mentioned in the question (and their findings):

• Cochrane (2016), based on 4 RCTs and one cohort study:

Our review findings have not identified conclusive evidence of benefit of HCW vaccination programmes on specific outcomes of laboratory-proven influenza, its complications (lower respiratory tract infection, hospitalisation or death due to lower respiratory tract illness), or all cause mortality in people over the age of 60 who live in care institutions.

• Dolan (2012) reviewed 20 papers of which 4 were RCTS, 10 observational studies and the rest reviews (thereof) to conclude that:

Consistency in the direction of effect was observed across several different outcome measures, suggesting a likely protective effect for patients in residential care settings. However, evidence was insufficient for us to confidently extrapolate this to other at-risk patient groups.

The CDC however has a page which is in favor:

The findings of a recent CDC review of related published literature indicate that influenza vaccination of health care personnel can enhance patient safety. [1,2]

where the two references are a review (Ahmed et al. 2014 based on 4 RCTs and 4 observational studies) and a commentary on it. I'll just quote from the review's abstract:

Influenza vaccination of healthcare personnel (HCP) is recommended in >40 countries. [...] the quality of the evidence for the effect of HCP vaccination on mortality and influenza cases in patients was moderate and low, respectively. The evidence quality for the effect of HCP vaccination on patient hospitalization was low. The overall evidence quality was moderate. CONCLUSIONS: The quality of evidence is higher for mortality than for other outcomes. HCP influenza vaccination can enhance patient safety.

And independently of those I found one review (Kliner (2016)) which reviewed... 11 reviews:

The evidence for employer and patient safety benefits of influenza vaccination is not straightforward and has been interpreted differently by different systematic review authors.

So, yeah, the number of reviews seems to exceed the number of actual RCTs on this (and even the number of observational studies). And they are all flogging the same evidence with a slightly different spin on the conclusion.