European countries signed up to Plan S can expect to have about half their total research output published in open access format, according to new analysis that offers a snapshot of the scheme’s potential global impact.

The Plan S Footprint: Implications for the Scholarly Publishing Landscape, published by research data analysts Clarivate, examines the extent to which existing publications comply with the guidelines for Plan S, under which participating funders will require all the research that they had supported to be made freely available at the point of publication from next January.

Plan S has so far won the support of 14 European national funders, the European Commission and three charitable funders, including the Wellcome Trust and the Bill & Melinda Gates Foundation.

While the papers funded by Plan S backers account for only about 6.4 per cent of total annual academic output, researchers found their impact to be much wider, with compliant papers racking up more citations on average, across all fields.

In molecular biology and genetics, for example, 2017 papers authored by one or more researchers supported by Plan S signatories received an average of 7.7 citations, compared with the total subject average of 4.7.

Papers that were funded by Plan S signatories were “well cited, published in high impact journals, and, often in journals from major publishing houses”, the paper concludes, adding that this would “influence the publishing landscape”.

Breaking down the figures by country, researchers deduced that “some European countries would publish more than 40 per cent of their output as open access”, reaching 50 per cent where the main national funder – for instance, the research councils that form UK Research and Innovation – is a Plan S supporter.

The report’s findings reflect positively on the scope of Plan S, challenging critics’ perceptions that the initiative will not manage to obtain a global reach. But the findings also point to potential challenges ahead for researchers, journals and publishers attempting to comply with the scheme.

“Hybrid” journals that offer a mix of subscription-only and open access papers will not be compliant, for example, and Plan S funders have set a three-year timeframe for this model to be phased out.

The paper estimates that about 90,000 papers funded by Plan S supporters which are currently published in hybrid or subscription journals would need to be “rehoused” if the titles did not flip to full open access.

“The relocation of content to open access titles would represent a 29 per cent overall movement in the volume of well-cited papers in the existing compliant venues,” the researchers add, which “could be disruptive in some subjects, and suitable compliant venues are not always available”.

Furthermore, researchers estimate the cost of such a movement at around €150 million (£128 million). “Meeting these costs will fall on research funders” through article processing charges, they say. “It is not evident whether marginal resources are available to support all affected authors.”

Meanwhile, Springer Nature has said that articles published in selected journals since November 2017 will be made available for download on authors’ ResearchGate profiles – a move that the publisher said would “remove barriers” to access and support the sharing of articles off-campus.

With 623 of its 2,923 titles available through full open access, Springer Nature faces increasing pressure to adapt its policies as the deadline for Plan S implementation approaches. A spokeswoman for the publisher said that the timing was “purely coincidental”.

rachael.pells@timeshighereducation.com